Difference between revisions of "Dog" - New World Encyclopedia

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{{Taxobox_begin | color = pink | name = Domestic Dog}}<br> <small>'''[[Wikipedia:Conservation status|Conservation status:]] Domesticated'''</small>[[Category:Domesticated animals]]
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{{Taxobox
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{{Taxobox_image | image = [[Image:YellowLabradorLooking wb.jpg|250px|Labrador Retriever]] | caption = '''[[Labrador Retriever]]'''<br>a breed of domestic dog}}
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| color = pink  
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{{Taxobox_begin_placement | color = pink}}
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| name = Domestic dog
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{{Taxobox_regnum_entry | taxon = [[Animal]]ia}}
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| fossil_range = Late [[Pleistocene]] - Recent
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{{Taxobox_phylum_entry | taxon = [[Chordate|Chordata]]}}
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| status = {{StatusDomesticated}}
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{{Taxobox_subphylum_entry | taxon = [[Vertebrate|Vertabrata]]}}
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| image = YellowLabradorLooking.jpg
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{{Taxobox_classis_entry | taxon = [[Mammal]]ia}}
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| image_width = 200px
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{{Taxobox_ordo_entry | taxon = [[Carnivora]]}}
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| image_caption = [[commons:Category:Canis lupus|other images of dogs]]
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{{Taxobox_familia_entry | taxon = [[Canidae]]}}
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| domain = [[Eukaryota]]
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{{Taxobox_genus_entry | taxon = ''[[Canis]]''}}
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| regnum = [[Animal]]ia
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{{Taxobox_species_entry | taxon = ''[[wolf|C. lupus]]''}}
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| phylum = [[Chordate|Chordata]]
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{{Taxobox_subspecies_entry | taxon = '''''C. l. familiaris'''''}}
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| classis = [[Mammal]]ia
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{{Taxobox_end_placement}}
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| ordo = [[Carnivora]]
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{{Taxobox_section_trinomial_parens | color = pink| trinomial_name = Canis lupus familiaris | author = [[Carolus Linnaeus|Linnaeus]] | date = 1758}}
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| familia = [[Canidae]]
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{{Taxobox_end}}
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| genus = ''[[Canis]]''
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| species = ''[[Gray Wolf|C. lupus]]''
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| subspecies = '''''C. l. familiaris'''''
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| trinomial = ''Canis lupus familiaris''
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}}
  
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'''Lesa, you can hit the "import" button on the images to import them. If I get time, I will do this, but if you are already at the article, you can do this. Then later i will follow the links to make sure that we don't have copyright problems.'''
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The '''dog''' ''(Canis lupus familiaris'' or ''Canis familiaris)'' is usually considered to be humankind's first, and perhaps most important, [[domestic animal]]. It generally is classified as a [[subspecies]] of the [[gray wolf]] ''(Canis lupus)'', a [[mammal]] of the [[Canidae]] family of the order [[Carnivora]].
  
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The '''dog''' is a [[mammal]] in the order [[Carnivora]]. Dogs were first [[Domestication|domesticated]] from [[Gray Wolf|wolves]] at least 17,000 years ago [http://news.bbc.co.uk/2/hi/science/nature/2498669.stm], but perhaps as early as 150,000 years ago based upon recent genetic fossil and [[DNA]] evidence{{ref|vila}}. In this time, the dog has developed into hundreds of breeds with a great degree of variation. For example, heights at the [[withers]] range from just a few inches (such as the [[Chihuahua (dog)|Chihuahua]]) to roughly three feet (such as the [[Irish Wolfhound]]), and colors range from white to black, with reds, grays (usually called ''blue''), and browns occurring in a tremendous variation of patterns.  
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The word "dog" also is used to refer to some other members of the Canidae family, for instance the bush dog ''(Speothos venaticus)'' of [[South America]] and the raccoon dog ''(Nyctereutes procyonoides)'' of [[Asia]]. The family Canidae itself often is called the "dog family" and includes [[jackal]]s and [[coyote]]s, which are closely related to dogs and wolves, as well as [[fox]]es, which are less closely related. Members of the Canidae family are called "canids."
  
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Dogs, like humans, are highly [[social animal]]s and this similarity in their overall behavioral pattern accounts for their trainability, playfulness, and ability to fit into human households and social situations.  This similarity has earned dogs a unique position in the realm of interspecies relationships. The loyalty and devotion that dogs demonstrate as part of their natural instincts as pack animals closely mimics the human idea of love, leading many dog owners to view their pets as full fledged family members. Conversely, dogs seem to view their human companions as members of their pack, and make few, if any, distinctions between their owners and fellow canines.  Dogs fill a variety of roles in [[human society]] and are often trained as [[working dog]]s. For dogs that do not have traditional jobs, a wide range of [[dog sports]] provide the opportunity to exhibit their natural skills. In many countries, the most common and perhaps most important role of dogs is as [[companion dog|companions]]. Dogs have lived with and worked with humans in so many roles that their loyalty has earned them the unique [[sobriquet]] "man's best friend." Conversely, some cultures consider dogs to be [[unclean animals|unclean]]. In other cultures, some dogs are used as [[taboo food and drink|food]].
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The trainability, devotion, playfulness, and ability to fit into human households have earned dogs a unique position in the realm of interspecies relationships. Dogs have lived and worked with humans in so many roles&mdash;hunting, herding and protecting [[sheep]] and [[cattle]], guarding people and property, rescuing people, companionship, and so forth&mdash;that their loyalty has earned them the unique sobriquet, "man's best friend." Their actions mimic the human idea of [[love]] and friendship, leading many dog owners to view their pets as family members.  
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{{toc}}
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In a process generally thought to span at least 14,000 years, humans have domesticated the dog, produced innumerable breeds, and bred and trained them to perform a great variety of useful services and sometimes dubious actions, including as guard dogs trained to instill fear in people and as sports dogs taught to fight other dogs to the death.
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[[File:Dog anatomy lateral skeleton view.jpg|thumb|Lateral view of a dog's bone structure.]]
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== Characteristics ==
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Dogs, like [[wolf|wolves]] and other canids, are specialized for a life of hunting and eating other animals. Their bodies are compact and muscular and their legs are long, which gives them speed and endurance for chasing prey. Their jaws are large and their teeth are well suited for grasping, biting, and tearing flesh.  Their [[digestive system]]s, however, are suited for some [[plant]] foods as well as flesh.
  
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==Terminology==
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Most dogs are covered with a thick coat of [[fur]], which protects them from the elements.  Alaskan malamutes and Siberian huskies, which originated in the [[Arctic]], are able to live outside without shelter in temperatures far below freezing. Dogs' coats come in a wide range of colors, including black, white, brown, yellow, red, and gray. They come in a range of lengths and textures from very short to long, either straight or curly (AKC 2006).
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The word "dog", in common usage, refers to the domestic pet dog, ''Canis lupus familiaris'' (originally classified as ''Canis familiaris'' by Linnaeus in 1758. In 1993, dogs were reclassified as a subspecies of the wolf, ''Canis lupus'', by the [[Smithsonian Institution]] and the [[American Society of Mammalogists]]. The word is sometimes used to refer collectively to any mammal belonging to the family [[Canidae]] (as in "the dog family"), such as wolves, foxes, and coyotes. The constellations [[Canes Venatici]], [[Canis Major]] and [[Canis Minor]] are of dogs.
 
  
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In breeding circles, a male canine is referred to as a dog while a female canine is a bitch. Offspring are generally called pups or puppies. A group of offspring is a litter. The process of birth is whelping. Many [[Mixed-breed dog#Terms for mixed-breed dogs|terms are used]] for dogs that are not purebred.
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A dog's [[heart]] and [[lung]]s are oversized relative to its body and its normal everyday needs. A dog also has relatively more [[red blood cell]]s than a human. Most of the time the dog will keep the extra red blood cells stored in its [[spleen]]. When the animal enters into a situation where its full [[metabolism]] is required, such as play, catching game, or fighting other dogs, the extra cells are released into the bloodstream.  The "oversized" heart and lungs would then be running at full capacity, and the animal would have an enhanced ability to engage in aerobic activity. This activity produces internal heat. Dogs, being covered in fur, are limited in their ability to cool down. After a short time the animal must either cease its athletic activity or risk harming itself from overheating. One can easily observe this pattern of intense activity followed by rest periods in puppies.  During the rest phase, the spleen collects red blood cells and the animal may pant to cool down.
  
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==Intelligence==
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Dogs, like most [[carnivore]]s, are naturally active only 4 to 6 hours each day and prefer to sleep the rest of the time (Kruuk 2002).
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Among dog lovers, dogs are generally valued for their intelligence, and [[anecdote|anecdotal]] evidence suggests that dogs have a reasonably high intelligence. For a detailed discussion on what dog intelligence is, see [[dog intelligence]].
 
  
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==Physical characteristics==
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Dogs, like other canids, are considered to be among the most intelligent of all animals, as shown by their ability to adapt to changing conditions in human society.  
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{{main|Dog anatomy}}
 
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[[Image:Roodog2k-ivan-and-boxer.JPG|thumb|The dog has developed into hundreds of breeds with a great degree of variation, such as this [[Miniature Pinscher]] and [[Boxer (dog)|Boxer]].]]
 
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Modern [[dog breed]]s show more variation in size, appearance, and behavior than any other domestic animal. Within the range of extremes, dogs generally share attributes with their wild ancestors, the [[Gray Wolf|wolves]]. Dogs are [[predator]]s and [[scavenger]]s, possessing sharp teeth and strong jaws for attacking, holding, and tearing their food. Although selective breeding has changed the appearance of many breeds, all dogs retain basic traits from their distant ancestors. Like many other predatory mammals, the dog has powerful muscles, fused wristbones, a [[cardiovascular]] system that supports both sprinting and endurance, and teeth for catching and tearing. Compared to the bone structure of the human foot, dogs technically walk on their toes.
 
  
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The dog's ancestor, the gray wolf, is the largest canid; with adults weighing between 18 and 80 kg (40 to 175 lbs).  Modern dogs can weigh anywhere from 1 to over 100 kg (2.2 to 220 lbs). Dingos, wild dogs of [[Australia]] which are descended from domestic dogs, average 10 to 20 kg (22 to 44 lbs) in weight (Nowak 1983).
  
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===Sight===
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===Senses===
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Dogs were thought to be [[dichromat]]s and thus, by human standards, [[color blind]].<sup>[[#References and further reading|1]], [[#References and further reading|2]]</sup> New research is now being explored that suggests that dogs may actually see some colour, but not to the extent that humans do. It has also been suggested that dogs see in varieties of purple/violet and yellow shades. Because the lenses of dogs' eyes are flatter than humans', they cannot see as much detail; on the other hand, their eyes are more sensitive to light and motion than humans' eyes. Some breeds, particularly the best [[sighthound]]s, have a field of vision up to 270° (compared to 180° for humans), although broad-headed breeds with their eyes set forward have a much narrower field of vision, as low as 180°.<sup>[[#References and further reading|1]], [[#References and further reading|2]]</sup>
 
  
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===Hearing===
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====Sight====
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[[Image:PennyAlertPricksEars.jpg|thumb|right|This [[Collie]]/[[Saluki]] cross pricks and angles her ears to find the source of a sound.]]
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In general, the vision of dogs is not as good as that of humans. They have only limited color vision, equivalent to red-green [[color blindness]] in humans (Alderton 1984).  They also are nearsighted compared to humans and can not see detail as well. The average dog's vision seems to be about 20/50 to 20/100, using the human standard. On the other hand they see better in dim light and may also detect motion better than humans (Davis 1998).
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Dogs detect sounds as low as the 16 to 20 [[Hertz|Hz]] frequency range (compared to 20 to 70 Hz for humans) and as high as 70,000 to 100,000 Hz (compared to 20,000 Hz for humans)<sup>[[#References and further reading|2]]</sup>, and in addition have a degree of ear mobility that helps them to rapidly pinpoint the exact location of a sound. Eighteen or more muscles can tilt, rotate and raise or lower a dog's ear. Additionally, a dog can identify a sound's location much faster than a human can, as well as hear sounds up to four times the distance that humans are able to. Those with more natural ear shapes, like those of wild canids like the fox, generally hear better than those with the floppier ears of many domesticated species.
 
  
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===Scenting===
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====Hearing====
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[[Image:Weimaraner wb.jpg|thumb|right|Some Dogs, like this [[Weimaraner]], are predators suited to chasing after, leaping at, and killing prey.]]
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[[Image:PennyAlertPricksEars.jpg|thumb|right|This [[mixed-breed dog]] angles her ears to find the source of a sound.]]
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Dogs have nearly 220 million smell-sensitive cells over an area about the size of a pocket [[handkerchief]] (compared to 5 million over an area the size of a [[postage stamp]] for humans). Some breeds have been selectively bred for excellence in detecting scents, even compared to their canine brethren. What information a dog actually detects when he is scenting is not perfectly understood; although once a matter of debate, it now seems to be well established that dogs can distinguish two different types of scents when trailing, an air scent from some person or thing that has recently passed by, as well as a ground scent that remains detectable for a much longer period. The characteristics and behavior of these two types of scent trail would seem, after some thought, to be quite different, the air scent being intermittent but perhaps less obscured by competing scents, whereas the ground scent would be relatively permanent with respect to careful and repetitive search by the dog, but would seem to be much more contaminated with other scents. In any event, it is established by those who train tracking dogs that it is impossible to teach the dog how to track any better than it does naturally; the object instead is to motivate it properly, and teach it to maintain focus on a single track and ignore any others that might otherwise seem of greater interest to an untrained dog. An intensive search for a scent, for instance searching a ship for contraband, can actually be very fatiguing for a dog, and the dog must be motivated to continue this hard work for a long period of time.
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The hearing of dogs is superior to humans. They can detect sounds that are lower and those that are higher in frequency. They also have a degree of ear mobility that helps them to rapidly pinpoint the exact location of a sound. Eighteen or more muscles can tilt, rotate, and raise or lower a dog's [[ear]]. Additionally, a dog can identify a sound's location much faster than a human can, as well as hear sounds up to four times the distance that humans are able to. Those with more natural ear shapes, like those of wild canids, generally hear better than those with the floppy ears of many domesticated species.
  
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===Direction and spatial sense===
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====Smell====
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It has been observed that a lost dog can often find its way home, sometimes traveling over long distances.{{fact}}
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[[Image:Bloodhund r54.jpg|left|thumb|Scent hounds, especially the Bloodhound, are known for their keen sense of smell]]
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Dogs have nearly 220 million smell-sensitive [[cell (biology)|cells]] over an area about the size of a pocket [[handkerchief]] (compared to 5 million over an area the size of a [[postage stamp]] for humans).  Some breeds have been selectively bred for excellence in detecting scents, even compared to their canine brethren.  
  
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===Weather detection===
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What information a dog actually detects when it is scenting is not perfectly understood. Although once a matter of debate, it now seems to be well established that dogs can distinguish two different types of scents when trailing: An air scent from some person or thing that has recently passed by, as well as a ground scent that remains detectable for a much longer period. The characteristics and behavior of these two types of scent trail would seem, after some thought, to be quite different, the air scent being intermittent but perhaps less obscured by competing scents, whereas the ground scent would be relatively permanent with respect to careful and repetitive search by the dog, but would seem to be much more contaminated with other scents. In any event, it is established by those who train tracking dogs that it is impossible to teach the dog how to track any better than it does naturally; the object instead is to motivate it properly, and teach it to maintain focus on a single track and ignore any others that might otherwise seem of greater interest to an untrained dog. An intensive search for a scent, for instance searching a ship for contraband, can actually be very fatiguing for a dog, and the dog must be motivated to continue this hard work for a long period of time.
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Dogs also have the ability to sense inclement weather (mainly [[thunderstorms]]) many miles away. This is due to their keen ability to detect fluctuations in [[barometric pressure]] and can explain a dog's anxiety before and during a storm. The evolutionary ability of sensing weather can be traced back to when wolves used it to move the pack into proper shelter before a dangerous storm.
 
  
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==Diet==
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===Reproduction===
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[[Image:Tessaenjoyingbone.JPG|thumb|This [[English Springer Spaniel]] is enjoying a bone.]]
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[[Image:CatahoulaLitter wb.jpg|thumb|right|A Catahoula leopard dog mother nursing her litter of puppies.]]
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{{see also|Dog health}}
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In domestic dogs, sexual maturity ([[puberty]]) begins to happen around age 6 to 12 months for both males and females, although this can be delayed until up to two years old for some large breeds. [[Adolescence]] for most domestic dogs is around 12 to 15 months, beyond which they are for the most part more adult than puppy. As with other domesticated species, [[domestication]] has selectively bred for higher [[libido]] and earlier and more frequent breeding cycles in dogs than in their wild ancestors.
  
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Presently, there is an academic discussion as to whether domestic dogs are [[omnivores]] or [[carnivores]].
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Dogs bear their litters roughly 9 weeks after [[fertilization]], although the length of gestation can vary from 56 to 72 days. A general rule of thumb is that a [[mammal]] will produce half as many offspring as the number of teats on the mother. This rule is altered in domesticated animals since larger litters are often favored for economic reasons and in dogs, particularly, the great range of sizes and shapes plays a role in how many healthy puppies a female can carry. An average litter consists of about six puppies, though this number may vary widely based on the breed of dog. Small dogs generally produce from one to four puppies in each litter, while much larger breeds may average as many as 12 pups in each litter. The number of puppies also varies with the mother's age and health, the father's [[sperm]] count, the timing of the breeding, and many other factors.
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The classification in the Order [[Carnivora]] does not necessarily mean that a dog's diet must be restricted to [[meat]]. Unlike an obligate carnivore, such as a [[cat]], a dog is not dependent on meat protein in order to fulfill its dietary requirements. Dogs are able to healthily digest a variety of foods including [[vegetable]]s and [[cereal|grains]], and in fact can consume a large proportion of these in their diet. Wild canines not only eat available plants to obtain key [[amino acids]], but may also obtain nutrients from vegetable matter from the stomach contents of their [[herbivorous]] prey. Domestic dogs can survive healthily on a reasonable and carefully designed [[vegetarian]] diet, particularly if [[egg (food)|eggs]] and [[milk]] products are included. Some sources suggest that a dog fed on a strict vegetarian diet may develop [[dilated cardiomyopathy]] since it lacks L-carnitine.{{ref|Nelson}}
 
  
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In the wild, these diets are typically pursued in the absence of available meat. It has also been noted that extremely stressful conditions, such as the [[Iditarod]] race and scientific studies of similar conditions, suggest that high-protein diets including meat help prevent damage to muscle tissue. This research is also true of other mammals.
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===Lifespan===
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The typical lifespan of dogs varies considerably by breed. For example, many giant dog breeds (such as great danes) average only 7 or 8 years, while some small terrier breeds, or toy breeds, might live to be older than 20. The average lifespan for mixed-breed and midsize dogs is about 13 to 14 years. The longest-lived dog with reliable documentation died at 29 years and 27 days; the breed of the dog was an Australian cattle dog and it lived in Virginia, [[United States]], with the date of death in 1939. Although the lifespans of all living species are mostly uncontrollable, one can significantly extend a dog's life by feeding it the right kinds of foods, giving it regular exercise, treating its [[disease]]s, caring for its special needs, and giving it love and comfort.
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Dogs sometimes eat grass, a harmless activity. Explanations abound, but rationales such as that it neutralizes acid are just guesses. Eating grass might make the dog vomit, so one explanation is that dogs eat grass to remove unwanted substances from their stomachs.  
 
  
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===Dangerous substances===
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===Social behavior===
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Some foods commonly enjoyed by humans are dangerous to dogs, including [[chocolate]] ([[Theobromine poisoning]]), [[onion]]s, [[grape]]s and [[raisin]]s, [[chewing gum|some types of gum]], [[Domesticated turkey|turkey]], [[Macadamia nut]]s, and [[hops]].
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Dogs, like almost all canids, are social animals. [[Wolf|Wolves]], and it is assumed the ancestors of dogs, almost always live in pairs, a male and a female with their young, or in larger groups called [[pack]]s. Within the pack, the individual animals communicate with each other by visual signals, such as body and facial expressions and tail wagging, as well as by vocal signals, such as growls and howls. Pack members sometimes hunt individually and sometimes as a group, depending on the situation, including the size of the prey (Kruuk 2002).
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Human medications should not be given to a dog as a substitute for their regular medication as some can be especially toxic, especially [[paracetamol]]/acetaminophen (Tylenol).
 
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[[Alcoholic beverage]]s pose much the same temptation and hazard to dogs as to humans.
 
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Dogs may also find some poisons attractive, including [[antifreeze]], snail bait, insect bait, and rodent poisons.
 
  
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==Reproduction==
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The members of the pack cooperate in many activities, such as hunting, caring for the young, and defending their territory from intruders. Within each pack, there is a dominant pair which takes the lead, while the others support them. In most cases, only the dominant pair reproduces. Wolves struggle to establish dominance and sometimes fight with each other, but this seldom leads to serious injury or death since the losing animal will display submissive behavior which discourages further attacks.  Studies of feral dogs have found that they often form packs of 3 to 5 individuals (Clutton-Brook 1999; Nowak 1993; Voelker 1986).
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[[Image:Shepador_Chewer.JPG|thumb|Puppies engage in [[teething]] on almost anything.]]
 
  
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Among professional breeders, dogs are only allowed to mate for a specific purpose. Sometimes dogs are bred to create puppies to sell, or sometimes to carry on an award-winning purebred line. Breeders who do this are usually experienced in this process. Dog breeders have access to records which allow them to accurately guess which characteristics will "breed true" in a particular dog. Dog breeders also have accurate information on the complexities of the reproductive process for the breed of dog that they are accustomed to handling. Dog owners may accidentally allow their pets to breed without regard to bloodlines.
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== Origins ==
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According to recent [[Genetics|genetic]] research, the lineage of dogs separated from that of wolves about 100,000 years ago (Wayne 1997). It is not known when the ancestors of dogs began to associate with humans. The first [[fossil]] evidence of domesticated dogs, which had changed in physical form from their wolf ancestors, dates from around 15,000 years ago. Dog fossils from about this time have been found in [[Asia]], [[Europe]], [[North America]], and [[South America]] (Clutton-Brock 1999).  
  
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===Fertility===
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Other genetic research seems to indicate that [[China]] was the site of the original domestication of dogs (McGourty 2002). Genetic research has identified 14 ancient dog breeds, with the oldest being the Chow Chow, Shar Pei, Akita Inu, Shiba Inu, and Basenji. Many of the 14 breeds are associated with China and Japan (Savolainen 2002).
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As with most domesticated species, one of the first and strongest effects seen from selective breeding is selection for cooperation with the breeding process as directed by humans. In domestic dogs, one of the behaviours that is noted is the abolition of the pair bond seen in wild canines. The ability of female domestic dog to come into [[estrus]] at any time of the year and usually twice a year is also valued. The amount of time between cycles varies greatly among different dogs, but a particular dog's cycle tends to be consistent through her life. This is also called ''in season'' or ''in heat''. Conversely, undomesticated canine species experience estrus once a year, typically in late winter.
 
  
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===Menarche===
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== Human relationships ==
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Most bitches come into season for the first time between 6 and 12 months, although some larger breeds delay until as late as 2 years. Like most mammals, the age that a bitch first comes into season is mostly a function of her current body weight as a proportion of her body weight when fully mature. The different rates of maturation are responsible for the [[menarche]], not the chronological age.
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Dogs are highly [[social animal]]s. This can account for their trainability, playfulness, and ability to fit into human households and social situations. This similarity has earned dogs a unique position in the realm of interspecies relationships.
  
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===Pregnancy and litters===
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The loyalty and devotion that dogs demonstrate as part of their natural instincts as pack animals closely mimics the human ideas of [[love]] and [[friendship]], leading many dog owners to view their pets as full-fledged family members. Conversely, dogs seem to view their human companions as members of their pack, and make few, if any, distinctions between their owners and fellow dogs.
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[[Image:CatahoulaLitter wb.jpg|thumb|right|A [[Catahoula Leopard Dog|Catahoula Leopard]] mother nursing her litter of puppies.]]
 
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A general rule of thumb is that a mammal will produce half as many offspring as the number of teats on the mother. This rule is altered in domesticated animals since larger litters are often favoured for economic reasons. Dogs bear their litters roughly 9 weeks after [[fertilization]]. An average litter consists of about six '''puppies''', though this number may vary widely based on the breed of dog. Since a mother can only provide nutrients and care to a limited number of offspring, humans must assist in the care and feeding when the litter exceeds approximately eight puppies. Some breeds have been developed to emphasize certain physical traits beyond the point at which they can safely bear litters on their own. For example, the [[Bulldog]] often requires [[artificial insemination]] and almost always requires [[cesarean section]] for giving birth.
 
  
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===Spaying and neutering===
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Dogs fill a variety of roles in human society and are often trained as working dogs. For dogs that do not have traditional jobs, a wide range of dog sports provide the opportunity to exhibit their natural skills. In many countries, the most common and perhaps most important role of dogs is as companions or pets. In the United States, about 36 percent of households own at least one dog, with the total number of animals about 62 million (AVMA 2002).  
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Spaying or neutering refers to the removal of the [[male]] [[testicle]]s or the female [[ovary|ovaries]] and [[uterus]], in order to eliminate the ability to procreate, and reduce sex drive.
 
  
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Dog experts advise that dogs not intended for further breeding should be spayed or neutered so that they do not have undesired puppies. Unwanted puppies are abandoned, eaten, or sometimes disposed of in a careless fashion. It is also common for stray adult dogs placed in animal shelters to be euthanized due to lack of resources.
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Dogs have lived and worked with humans in so many roles that their loyalty has earned them the unique sobriquet, "man's best friend."
  
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[[Spaying and neutering]] can also help prevent hormone-driven diseases such as mammary cancer and prostate cancer, as well as undesired hormone-driven behaviors. The hormonal changes involved with sterilization are likely to somewhat change the animal's personality, and some object to this angle as the sterilization in itself could be carried out without the excision of organs.
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==Terminology==
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The [[English language|English]] word "dog," in common usage, refers to the domestic [[pet]] dog, ''Canis lupus familiaris.'' The species was originally classified as ''Canis familiaris'' by Linnaeus in 1758. In 1993, dogs were reclassified as a subspecies of the gray wolf, ''Canis lupus,'' by the [[Smithsonian Institution]] and the American Society of Mammalogists.  
  
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Contrary to myth, it is not required for a female dog to either experience a heat cycle or have puppies before spaying, and likewise, a male dog does not need the experience of mating before neutering; these myths are responsible for numerous unnecessary health problems and unwanted puppies. Female dogs spayed before their first heat have a vastly lower incidence of many forms of cancer than dogs which are spayed after their first heat or pregnancy. A female dog can become pregnant on her first heat cycle (which can take place as early as six months), and should be kept away from intact male dogs, including littermates, over the age of 4 months. Many veterinarians recommend that owners neuter/spay their pets around the age of 5 months.
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The English word "dog" might derive from the Old English "''docga,''" a "powerful breed of canine," like the modern mastiff.  The English word "hound" is a cognate of German ''Hund,'' Dutch ''hond,'' common Scandinavian ''hund,'' Icelandic ''hundur,'' which, though referring to a specific breed in English, means "dog" in general in the other Germanic languages. "Hound" itself derives from the [[Proto-Indo-European language|Proto-Indo-European]] *kwon-, which is the direct root of the Greek κυων (kuōn) and the indirect root of the Latin [[canis]] through the variant form *kani-.
  
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The various animal control agencies of the United States and the [[ASPCA]] urge pet owners to help reduce the number of unnecessary deaths of thousands of unwanted animals by having pets spayed or neutered.
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In breeding circles, a male canine is referred to as a "dog," while a female canine is called a "bitch." The father of a litter is called the "sire," and the mother of a litter is called the "dam." Offspring are generally called "pups" or "puppies" until they are about a year old. A group of offspring is a "litter." The process of birth is "whelping." Many terms are used for dogs that are not purebred.
  
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==Dog health==
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The [[constellation]]s Canes Venatici, Canis Major, and Canis Minor are named from the [[Latin language|Latin]] word for "dog," for their perceived resemblance to dogs. [[Sirius]], the brightest [[star]] in the sky as seen from earth, is called the "dog star" because it is found in Canis Major. The time when Sirius rises just before sunrise, mainly July and August, are called the "dog days of summer."
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{{main|Dog health}}
 
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{{further|[[:Category:Dog health]]}}
 
  
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Dogs are susceptible to various diseases, ailments, and poisons, some of which affect humans in the same way, others of which are unique to dogs.
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==Breeds==
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===Diseases===
 
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Diseases commonly associated with dogs include [[rabies]] (hydrophobia), [[canine parvovirus]], [[canine distemper]], and [[pulmonic stenosis]], although there are many others.
 
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===Parasites===
 
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Common external parasites are various species of [[flea]]s, [[tick]]s, and [[mites]]. Internal parasites include [[hookworm]]s, [[tapeworm]]s, [[roundworm]]s, and [[heartworms]].
 
  
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===Common physical disorders===
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Different breeds of dogs emerged over time due to environmental factors and human selection.  In ancient [[Egypt]], dogs looking like the modern greyhound and the mastiff are pictured in art. In ancient [[Roman]] writings, miniature pet dogs like modern toy breeds are mentioned (Clutton-Brook 1999).
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Some breeds of dogs are also prone to certain genetic ailments, such as [[hip dysplasia]], [[luxating patella]]s, [[cleft palate]], [[blindness]], or [[hearing impairment|deafness]]. Dogs are also susceptible to the same ailments that humans are, including [[Diabetes in cats and dogs|diabetes]], [[epilepsy]], [[cancer]], and [[arthritis]]. [[Gastric torsion]] and [[bloat]] is a dangerous problem in some large-chested breeds.
 
  
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===Lifespan===
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There are said to be over 450 different dog breeds in the world. As of 2006, the American Kennel Club recognized 153 breeds, divided into 7 groups (AKC 2006):
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{{main|Dog years}}
 
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The typical lifespan of dogs varies considerably by breed. For example, many giant dog breeds average only 7 or 8 years, while some small terrier breeds might live as long as 20 years. The average lifespan for mixed-breed and midsize dogs is about 13 to 14 years. The longest-lived dog with reliable documentation died at 29 in 1939.
 
  
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==Behavior==
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* '''Sporting breeds''' were originally bred and trained to assist gun-wielding hunters in finding and recovering [[bird]]s and other small game. They include various pointers, spaniels, and retrievers.
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[[Image:Dog retrieving stick.jpg|thumb|250px|Most dogs can be trained to retrieve.]]
 
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All dogs have a tremendous capacity to learn complex social behavior and to interpret varied body language and sounds, and, like many predators, can react to and learn from novel situations. The requirements of coordinating complex social behavior requires that canines have the ability to sense and deliver a wide variety of cues via body language, more so than for even humans, who can use language for the same purpose. Physiologically, this correlates with such features as a large number of nerves innervating the facial muscles of dogs, allowing subtle control of a wide variety of facial expressions; in contrast to [[cats]], for instance, who have far fewer nerves governing their facial muscles, resulting in a smaller repertoire or "vocabulary" of expressions. This ability to read and deliver nonverbal cues makes dogs expert at reading human beings, as well, often even more so than other humans are, who rely on language. Most dog owners have a large collection of stories about their dogs recognizing individuals by their footsteps outside the door, and so on.
 
  
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Much of dog behavior can be correlated to pack behavior. Being pack animals, dog instinctively need to be around other animals.  Due to this behavior, dogs will submit to humans and obey commands.  This is probably why they have thrived so much in our society.
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* '''Hounds''' were bred to track and engage larger hunted animals. They include the bloodhound, the English foxhound, and the beagle.
  
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Dogs are very energetic as pups, particularly between 3 months and 1 year old, and some remain nearly as active and playful all their lives. Puppies love to play with toys and run, which helps muscle and bone development and improves their cardiovascular condition.  
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* '''Working breeds''' were bred for various tasks; such as guarding people, livestock, and property; pulling sleds; and rescuing people from water or snow. They include the rotweiler, the saint bernard, and the akita.
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<!-- Add mention of genetic uniqueness of dogs to comprehend human social cues —>
 
  
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===Interactions between Dogs and Humans===
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* '''Terriers''' were originally bred to catch and kill small animals, especially [[rat]]s, without the help of a human hunter. Popular terriers include the airedale terrier and the Parson Russell terrier (also called the Jack Russell terrier).
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{{main|Dog society}}
 
  
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The relationship between dogs and humans is rooted in history and dogs coexist with humans in a variety of ways. Dogs thrive in small social groups or [[pack (canine)|packs]] which, from their viewpoint, can include humans. Dog society can be thought of as dog packs characterized by a companionate hierarchy, in which each individual has a rank, and in which there is intense loyalty within the group. Dogs thrive in human society because their relationships with humans mimic their natural social patterns. The dog is always aware of its rank relative to other individuals in the group. An assertive dog may consider itself the alpha animal, considering its human master to be subordinate.  In healthy relationships, where the dog is expected to obey its human, the human is more often than not the alpha or leader.
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* '''Toy Breeds''' are smaller dogs bred to be pets. They include the pug, the pekingese, and the chihuahua.
  
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===Dogs as working partners===
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* '''Non-sporting breeds''' are medium-sized or large dogs bred to be pets, or in the case of the dalmation, a companion to [[horse]]s. The poodle is one of the most popular non-sporting breeds.
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Many breeds of dogs are commonly used as [[working dogs]]. There are [[service dogs]], [[guard dog]]s, [[hunting dog]]s, and [[herding dog]]s. Dogs have served as [[Guide dog|guides]] for the [[blindness|blind]], as [[commando]]s, and have flown into [[outer space]]. Most modern working dogs are put in positions that capitalize on their sensory prowess or strength and endurance advantages over normal humans. Dogs are also used for searching for or rescuing people and animals, such as in avalanches, at disaster sites, and for missing people or pets.
 
  
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===Dogs as hunting and sporting partners===
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* '''Herding breeds''' were bred to herd [[sheep]] or [[cattle]].  They include the collie, the German shepherd, and the Old English sheepdog.
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Many people compete with their dogs in a variety of [[dog sports]], including [[dog agility|agility]], [[flyball]], and many others. This often strengthens the bond between human and dog, since they must trust one another in a variety of environments and must learn how the other works and thinks.
 
  
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Dogs have been used as hunting companions since prehistory; hunting and guarding are probably the oldest uses for dogs.<!--reference: Fogle; not sure how to add an appropriate foonote to existing reference —> Today, [[hunting dog]]s are still widely used in many capacities, for finding, tracking, chasing, retrieving, or killing game, and dozens of breeds have been specialized to do certain types of hunting tasks very well. For example, scent hounds excel at following a trail using their noses; retrievers excel at bringing back birds that a hunter has shot; and there are many other specialties.
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Through history different dog breeds have gone in and out of fashion. In England, the King Charles Spaniel fell out of favor in 1689 when the house of Stuart was overthrown in the [[Glorious Revolution]] and was reborn in the twentieth century as the Cavalier King Charles Spaniel. In the United States, the beagle became very popular in the 1960s because of the cartoon character [[Snoopy]]. The most popular breed in the United States today is the Labrador retriever (AKC 2006).
  
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===Dogs as pets===
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==Mixed breed dogs==
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[[Image:Nap006b.jpg|right|thumb|200px|A 9 year old English [[Collie]] cross. Some say [[Mixed-breed dog|mongrels]] make the best pets.]]
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[[Image:Working dog edit.jpg|thumb|left|Mixed-breed dogs, such as this Australian Border Collie cross, are often desired as working animals for their robust health and intelligence.]]
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The majority of dogs in the world are of mixed breed or no definite breed. It is estimated that 60 percent of dogs in the [[United States]] are mixed breeds, and the number it thought to be much higher in poorer countries. Advocates of mixed breed dogs as working dogs and pets say that they are more intelligent and have fewer health problems than purebreds (Kilcommons 1996).
  
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Relationships between humans and dogs are often characterized by strong emotional bonds. Consequently, dogs are popular as [[pet]]s and companions, independent of any [[utilitarian]] considerations. Many dog owners consider having unconditional acceptance from a friend who is always happy to see them to be quite utilitarian, particularly if the dog also leads them to regular exercise. Empirically, dogs are quite dependent on human companionship and may suffer poor health in their absence. Many dogs are reported to have [[separation anxiety]] if their owner is away for an extended period of time.
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==Working, utility, and assistance dogs==
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[[Image:Labrador Retriever assistance dog.jpg|thumb|Labrador retrievers are often used as assistance dogs.]]
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[[Image:Belgian Shepherd Malinois on top of tank.jpg|thumb|Belgian Malinois war dog.]]
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The first ways that dogs were useful to humans were as helpers in hunting and as protectors. These roles grew out of the dogs' natural instincts. As time went on, dogs were trained to perform other tasks and were specially breed to do so. Some of the modern types of working dogs are:
  
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Some research demonstrates that dogs are able to convey a depth of emotion not seen to the same extent in any other animal; this is purportedly due to their closely-knit development with modern man, and the survival-benefits of such communication as dogs became more dependent on humans for sustenance.
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* '''Assistance dogs''' help the seeing and hearing-impaired. Others are trained to help those with [[epilepsy]] and psychiatric disorders, by detecting the onset of the condition so they can seek help. The typical assistance dog is a sociable breed such as a Labrador retriever. In the United States, people with assistance dogs are guaranteed access to public places by law.
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* '''Detection dogs'''  are trained to, and work at, using their senses (almost always the sense of smell) to detect substances such as explosives or [[illegal drugs]].
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* '''Guard dogs''' are trained to protect people and property. These are commonly doberman pinschers, German shepherds, and rottweilers, or mixes of these breeds. Guard dogs differ from '''watch dogs''' in that they are expected to engage an intruder, while watch dogs are only expected to bark to alert the property owner.
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* '''Herding dogs''' are trained to control livestock in the range. Sheepdogs and collies are common breeds.
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* '''Hunting dogs''' search for and retrieve game. Pointers and retrievers are typical hunting breeds.
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* '''Police dogs,''' typically German shepherds, are trained to assist law enforcement officers, often apprehending fleeing suspects. ''Schutzhund'' is a special test developed in [[Germany]] in the early 1900s to test if a German shepherd has the right talents and temperment to be successfully trained as a police dog.
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* '''Rescue dogs''' are those that search for missing humans. The archetypal breeds are the Saint Bernard and the bloodhound, although any dog with a good sense of smell can be trained to perform this task. One of the most famous dog rescues in history is that of [[Napoleon Bonaparte]], a poor swimmer, who fell into the ocean one night in 1814, and was rescued by a Newfoundland.
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* '''Show dogs''' do tricks for the entertainment of audiences. Poodles and American Eskimo dogs were very popular as show dogs in [[circus]]es and traveling shows in the past.  Now many types of dog perform in [[Motion picture|movies]] and [[television]].
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* '''Therapy dogs,''' with friendly and gentle temperaments, are trained to provide comfort and affection to hospitalized and institutionalized patients. The modern concept of the therapy dog was begun in 1976 by Elaine Smith, an American [[nurse]].
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* '''War dogs''' are used by the military to detect mines and enemy soldiers. War dogs, looking much like modern mastiffs, are pictured in ancient [[Assyria|Assyrian]] art. Dogs continued to be used in war through Roman and Medieval times. In 1560, Queen [[Elizabeth I]] of England sent 8,000 war dogs, equipped with spiked collars and coats of mail, with her army sent to [[Ireland]] to suppress a rebellion (Kilcommons 1996). In [[World War II]], the Soviet army trained dogs to carry explosives and run under enemy tanks, blowing them up.
  
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Nevertheless, it is often unwise to [[anthropomorphize]] the responses of dogs. Despite understandably positive interpretations by dog owners, it is questionable whether these animals are truly capable of feeling emotions on a human level. More research is needed to determine the [[dog intelligence|intelligence level of dogs]], and the motivations behind their responses to their masters.
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==Show and sport (competition) dogs==
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[[Image:English-Springer-Spaniel.jpg|thumb|An English Springer spaniel in a dog show]]
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[[Image:BC_eye.jpg|thumb|The border collie uses a direct stare at sheep, known as "the eye," to intimidate while herding at a trial.]]
  
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===Attacks on humans and livestock===
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Owners of dogs often enter them in competitions, whether show (breed conformation shows) or sports, including dog racing and dog sledding. The winners garner both prestige and prize money. These dogs are often bred specifically for competition, which may not be entirely beneficial for the breeds, due to the magnification of hereditary defects.
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{{main|Dog attack}}
 
  
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Humans have a tendency to [[anthropomorphize]] animals, particularly pets such as dogs, which are generally portrayed as being "man's best friend". Because of this, people often mistakenly expect a dog to react to situations and scenarios in much the same way as a human would, sometimes leading to unfortunate circumstances.
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* '''Dog agility''' is a sport in which dogs complete a timed obstacle course.  It is a fairly new sport, started in 1978 in the [[United Kingdom]].
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* '''Tracking trials'''  encourage dogs to make use of their strongest facility by emulating the finding of a lost person or article in a situation where the performance of the dog can be fairly assessed. Because of this, the tracks laid are not the wanderings, which may characterize a lost person, nor do they include deliberate attempts by the tracklayer to deceive the following dog.
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*'''Dogsled racing''' is a winter sport where a team of dogs pull a sled and driver (called a musher). The Iditarod Trail Sled Dog Race is perhaps the most famous of these races. Dog sledding is an ancient form of transportation and still a very effective way of moving freight across this type of terrain. Most modern dog sledders use mixed breed dogs.
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* '''Dog racing,''' almost always emphasizing greyhounds, involves dogs racing at betting tracks in a sport not unlike horse racing, reaching speeds of 40 miles per hour. Elsewhere, dachshunds are often raced, as a humorous sidelight in charity events.
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*'''Dog fighting''' and '''dog baiting''' are blood sports involving dogs. In the past, they were very popular but now they are illegal in most jurisdictions, but are still occasionally performed underground. Some of the breeds which have been used in dog fighting are the akita, the Irish terrier, and the American pit bull terrier (often called the pit bull). 
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* '''Disc dog''' is the more generic name for what is commonly called  '''Frisbee dog.'''  In disc dog competitions, dogs and their human disc throwers compete in events such as distance catching and somewhat choreographed freestyle catching. The sport celebrates the bond between handler and dog, by allowing them to work together. The term "disc" is preferred because "Frisbee" is a trademark (held by Wham-O) for a brand of flying disc.
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* '''Flyball''' is an event in which teams of dogs race against each other from a start/finish line, over a line of hurdles, to a box that releases a tennis ball to be caught when the dog presses the spring loaded pad, then back to their handlers while carrying the ball. Flyball has become popular because it is a sport in which all sizes and breeds of dog can compete.
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* '''Sheepdog trials''' (or simply '''dog trials''') are competitive events in which herding dog breeds move [[sheep]] around a field, fences, gates, or enclosures as directed by their handlers. Such events are particularly associated with hill farming areas, where sheep range widely on largely [[fence|unfenced]] land. These trials are popular in the [[United Kingdom]], [[Ireland]], [[South Africa]], [[Canada]], the [[United States]], [[Australia]], [[New Zealand]], and other farming nations.  Some venues allow only dogs of known herding breeds to compete; others allow any dog that has been trained to herd.
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* '''Earthdog trials''' test dachshunds and small terriers for their working abilities and instinct. Earthdog den trials involve underground tunnels that dogs must negotiate, while scenting a rat, the "quarry." The dog must follow the scent to the quarry and then "work" the quarry. Depending on the sanctioning organization, “working” means barking, scratching, staring, pawing or such at it, although the quarry is protected at all times.
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* '''Field trials''' are highly competitive events at which hunting dogs compete against one another. Field trials are organized by kennel clubs or other gun dog organizations.
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* '''Obedience trials''' are events in which a dog must perfectly execute a predefined set of tasks when directed to do so by its handler. Obedience competition provides an opportunity for a person and a dog to work as a highly tuned team.
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* '''Dog shows''' involve purebreds entered in conformation dog show and evaluated by how closely they match the ideal characteristics of the breed. The Westminster Kennel Club Dog Show is one of the most famous of this type of competition.
  
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After thousands of years of domestication and selective breeding for dogs whose aggression towards humans often goes no further than a ferocious bark that strongly indicates dislike of a human behavior, most dogs are unlikely to attack people. However, their sharp teeth and claws can inflict injury in an attack; a large dog can knock a human down. Provocation can range from something as seemingly innocuous as a toddler pulling a dog's tail, in which case the dog might nip to discourage the behavior, to something completely unobvious to humans, such as an odor or a movement that sets a dog off, to blatant human aggression or violence towards a dog, causing it to defend itself. There are hundreds of shades of provocation that may or may not lead to an attack upon a human. Canine aggression upon humans is ordinarily not tolerated, but any human aggression against an animal having formidable means of self-defense is foolhardy in the extreme.
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==Dogs in research==
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Dogs have long been used as subjects of [[scientific research]]. In the 1890s, the Russian scientist [[Ivan Pavlov]] used dogs to study psychological conditioning. Much of the research which led to the discovery of [[insulin]] and to the successful treatment of [[diabetes]] in humans was carried out using dogs as experimental subjects. On November 3, 1957, a Russian dog, Laika, became the first animal to orbit the earth.
  
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With formidable skills and weapons as hunters as well as large and unfussy appetites, dogs often menace livestock and wildlife. In most jurisdictions, dogs are killed for killing other creatures, so dogs should be prevented from any encounter with livestock or wildlife that might lead to a predatory response. The same creatures that [[Gray Wolf|wolves]], [[coyote]]s, and [[fox]]es attack as prey, especially sheep and poultry, are similarly attractive prey to dogs.
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Dogs presently make up only a small percentage of animals used in research; [[rat]]s and [[Mouse|mice]] far outnumber them. However, they are especially important in medical studies, for instance on the effects of drugs.  Among the reasons for this are their fairly large size and their ease in being taken care of and controlled.
  
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===Abandoned dogs===
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Beagles are especially popular for research because of their calm and friendly nature. Most research beagles are especially bred for this purpose. Other research dogs are obtained from various sources including pound seizure, newspaper ads, strays, and lost or stolen pets. Over the years there have been protests against the treatment of research dogs and laws have been passed to protect them, and in some cases to prevent former pet dogs from being used in research (HSUS 2007).
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[[Image:DSC6270.jpg|right|thumb|Abandoned dogs sometimes end up at no kill animal shelters.]]
 
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Wild dogs are shot by farmers in an effort to protect [[livestock]]. Bodies are sometimes tied to fences as warning to other dogs, especially in rural [[United States]] and [[Canada]]. Abandoned domestic dogs who become [[feral]] are particularly dangerous; they lack the survival skills of wild canines, as well as the genetic and learned fear of the humans' world. Feral dogs often form predatory packs that attack livestock and occasionally also prove dangerous to humans.
 
  
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In the UK, it is illegal to kill dogs, even if they are on your private land; you are required to contact your local [[Police]] Force, [[DogsTrust]], or the local branch of the [[RSPCA]], who will arrange its collection.
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==Dog health==
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Dogs are susceptible to various [[disease]]s, ailments, and poisons, some of which effect humans in the same way, others of which are unique to dogs.  
  
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==Ancestry and history of domestication==
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===Diet===
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[[Image:DogMosaic wb.jpg|thumb|This ancient mosaic, likely Roman, shows a large dog with a collar hunting a lion.]]
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At present, there is some debate as to whether domestic dogs should be classified as [[omnivore]]s or [[carnivore]]s, by diet.
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[[Molecular systematics]] indicate that the domestic dog (''Canis lupus familiaris'') descends from one or more populations of wild wolves (''Canis lupus''). As reflected in the [[nomenclature]], dogs are a subspecies of wolf and are thus still able to interbreed with wolves.  
 
  
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The relationship between man and canine has deep roots. [[Wolf]] remains have been found in association with [[hominid]] remains dating from 400,000 years ago. Converging archaeological and genetic evidence indicate a time of [[domestication]] in the late [[Upper Paleolithic]] close to the [[Pleistocene]]/[[Holocene]] boundary, between 17,000 and 14,000 years ago. [[Fossil]] bone morphologies and genetic analysis of current and ancient dog and wolf populations have not yet been able to conclusively determine whether all dogs descend from a single domestication event, or whether dogs were domesticated independently in more than one location. Domesticated dogs may have interbred with local populations of wild wolves on several occasions (so-called introgression).
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The classification in the Order [[Carnivora]] does not necessarily mean that a dog's diet must be restricted to [[meat]]; unlike an obligate carnivore, such as the [[cat]] family with its shorter [[small intestine]], a dog is dependent on neither meat-specific [[protein]] nor a very high level of protein in order to fulfill its basic dietary requirements. Dogs are able to healthily digest a variety of foods including [[vegetable]]s and [[cereal|grains]], and in fact dogs can consume a large proportion of these in their diet. Wild canines not only eat available plants to obtain [[amino acid#Essential amino acids|essential amino acid]]s, but also obtain nutrients from vegetable matter from the stomach and intestinal contents of their herbivorous prey, which they usually consume.  
  
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The earliest dog fossils, two crania from Russia and a mandible from Germany, date from 13,000 to 17,000 years ago. Their likely ancestor is the large northern [[Holarctic]] wolf, ''Canis lupus lupus''. Remains of smaller dogs from [[Mesolithic]] ([[Natufian]]) cave deposits in the Middle East, dated to around 12,000 years ago, have been interpreted as descendants of a lighter Southwest Asian wolf, ''Canis lupus arabs''. [[Rock art]] and skeletal remains indicate that by 14,000 years ago, dogs were present from North Africa across Eurasia to North America. Dog burials at the [[Mesolithic]] cemetery of [[Svaerdborg]] in Denmark suggest that in ancient Europe dogs were valued companions.
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Domestic dogs can survive healthily on a reasonable and carefully designed [[vegetarian]] diet, particularly if [[egg (food)|eggs]] and [[milk]] products are included. Some sources suggest that a dog fed on a strict vegetarian diet may develop dilated cardiomyopathy since it lacks L-[[carnitine]] (Nelson 2003), however, maintaining a balanced diet is also a factor since L-carnitine is found naturally in many nuts, [[seed]]s, [[bean]]s, [[vegetable]]s, [[fruit]]s, and [[whole grain]]s. In the wild, dogs can survive on a vegetarian diet when animal prey is not available. However it has been noted, both by observation of extremely stressful conditions such as the Iditarod Trail Sled Dog Race and by scientific studies of similar conditions, that high-protein (approximately 40 percent) diets including meat help prevent damage to [[muscle]] tissue. (This research is also true for some other mammals.) This level of protein corresponds to the percentage of protein found in the wild dog's diet when prey is abundant; higher levels of protein seem to confer no added benefit.
  
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Genetic analyses have so far yielded divergent results. Vilà, Savolainen, and colleagues (1997) concluded that dogs split off from wolves between 75,000 and 135,000 years ago, while a subsequent analysis by Savolainen et al. (2002) indicated a "common origin from a single gene pool for all dog populations" between 40,000 and 15,000 years ago in East Asia. Verginelli et al. (2005), however, suggest both sets of dates must be reevaluated in light of recent findings showing that poorly calibrated molecular clocks have systematically overestimated the age of geologically recent events. On balance, and in agreement with the archaeological evidence, 15,000 years ago is the most likely time for the wolf-dog divergence.
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===Spaying and neutering===
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In the United States, most pet dogs are spayed or neutered. Spaying is the surgical removal of the female's [[ovaries]] and [[uterus]]. Neutering is the removal of the male's [[testicles]]. Spayed and neutered dogs avoid some diseases such as breast and testicular [[cancer]].  Behaviors such as urinating in the house, running away, and aggression are also reduced; and unwanted litters of puppies are avoided, which could contribute to the problem of stray and feral dogs (ASPCA 2014).
  
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Verginelli examined ancient [[DNA]] evidence from five prehistoric Italian [[canids]] carbon-dated to between 15,000 and 3,000 years old, 341 wolves from several populations worldwide, and 547 purebred dogs. Their results indicate multiple independent origins of dogs and/or of frequent interbreeding between early proto-dogs and wolves throughout a vast geographic range. The detailed history remains unexplored and until further evidence is available, the following section on wolf ancestors must be considered purely speculative.
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===Diseases===
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Infectious diseases commonly associated with dogs include [[rabies]] (hydrophobia), canine parvovirus, and canine distemper. Congenital diseases of dogs can include a wide range from hip dysplasia and medial patellar luxation to [[epilepsy]] and [[pulmonic stenosis]]. Canines can get just about anything a human can get (excluding many infections, which are species specific) like hypothyroidism, cancer, dental disease, heart disease, [[Addison's disease]], and so forth.  
  
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===Wolf ancestors===
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Two serious medical conditions affecting dogs are [[pyometra]], affecting unspayed females of all types and ages, and [[bloat]], which affects the larger breeds or deep chested dogs. Both of these are acute conditions, and can kill rapidly; owners of dogs which may be at risk should learn about such conditions as part of good animal care.
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Although all wolves belong to the species ''[[Gray Wolf|Canis lupus]]'', there are (or were) many subspecies that had developed a distinctive appearance, social structure, and other traits. For example, the [[Japanese Wolf]] and the [[Eastern Timber Wolf]] possess different distinctive colouration, hunting and social structures.
 
  
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The [[Indian Wolf]] is thought to have contributed to the development of more breeds of dogs than other subspecies. Many of today's wild dogs, such as the [[dingo]], the [[dhole]] and [[pariah dog]]s, are descended from this wolf.  
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===Parasites===
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Common external parasites are various species of [[flea]]s, [[tick]]s, and [[mite]]s. Internal parasites include [[hookworm]]s, [[tapeworm]]s, [[roundworm]]s, and [[heartworms]].  
  
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The [[Indian wolf]] is also thought to have bred with descendants of the European wolf to create the [[Mastiff]]s and eventually leading to the development of such diverse breeds as the [[Pug]], the [[St. Bernard (dog)|Saint Bernard]], and the [[Bloodhound]]. The [[Tibetan Mastiff]] is an example of an ancient breed.
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===Common physical disorders===
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Some breeds of dogs are also prone to certain genetic ailments, such as [[hip dysplasia]], [[luxating patella]]s, [[cleft palate]], [[blindness]], or [[hearing impairment|deafness]]. As noted, dogs are also susceptible to the same ailments that humans are, including [[diabetes]], [[epilepsy]], [[cancer]], and [[arthritis]].
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The [[European wolf]], in turn, may have contributed many of its attributes to the [[Spitz]] dog types, most [[terrier]]s, and many of today's [[sheepdog]]s. The [[Chinese wolf]] is probably ancestor to the [[Pekingese]] and toy [[spaniel]]s, although it is also probable that descendants of the Chinese and European wolves encountered each other over the millennia, contributing to many of the oriental [[toy dog|toy]] breeds.
 
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The [[Eastern Timber Wolf]] is a direct ancestor to most, if not all, of the North American northern [[sled dog]] types. This interbreeding still occurs with dogs living in the [[Arctic]] region, where the attributes of the wolf that enable survival in a hostile environment are valued by humans. Additionally, unintentional crossbreeding occurs simply because dogs and wolves live in the same environment. The general [[reproductive isolation]] which is required to define dogs and wolves as separate species is purely a result of lack of opportunity, stemming from a general mutual unfamiliarity, suspicion, mistrust, and fear.
 
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The [[phenotype|phenotypic]] characteristic that distinguish a wolf from a dog are tenuous. Wolves typically have a "brush tail" and erect ears. While some dog breeds possess one of these characteristics, they rarely possess both.
 
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===Speed of domestication===
 
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Current research indicates that domestication, or the attributes of a domesticated animal, [http://www.amsci.org/amsci/articles/99articles/Trut.html#26879 can occur much more quickly] than previously believed. Domestication of a wild dog may occur within one or two human generations with deliberate [[selective breeding]]. It is also now generally believed that initial domestication was through mutual desire. Wild canines who scavenged around human habitations received more food than their more skittish or fearful counterparts. Canines who attacked people or their children were likely killed or driven away, while those more friendly animals survived. Canines would have been beneficial by chasing away other [[vermin]] or [[scavengers]]. With their sharp senses, they would also be valuable as an alarm against marauding predators. The relationship is theorized to have developed in this way.
 
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===Dogs as food===
 
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:''Main article: [[Dog meat]]''
 
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In a number of countries around the world, apart from being kept as pets, certain breeds of dogs are [[slaughter]]ed as a source of meat and specifically raised on farms for that purpose. In countries where dogs are particularly popular as household pets, the use of dogs as a source of food is often considered a taboo and abhorrent cultural practice.
 
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==Dog breeds==
 
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There are numerous [[dog breeds]], [[List of dog breeds|over 800]] being recognized by various [[kennel club]]s worldwide. As all dog breeds have been derived from mixed-breed dog populations, the term "purebred" has meaning only with respect to a certain number of generations. Many dogs, especially outside the United States and Western Europe, belong to no recognized breed.
 
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A few basic [[:Category:Dog types|breed types]] have evolved gradually during the domesticated dog's relationship with man over the last 10,000 or more years, but most modern breeds are of relatively recent derivation. Many of these are the product of a deliberate process of [[artificial selection]]. Because of this, some breeds are highly specialized, and there is extraordinary morphological diversity across different breeds. Despite these differences, dogs are able to distinguish dogs from other kinds of animal.
 
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The definition of a dog breed is a matter of some controversy. Depending on the size of the original founding population, closed gene pool breeds can have problems with inbreeding, specifically due to founder effect. Dog breeders are increasingly aware of the importance of population genetics and of maintaining diverse gene pools. Health testing and new DNA tests can help avoid problems, by providing a replacement for natural selection. Without selection, inbreeding and closed gene pools can increase the risk of severe health or behavioural problems. Some organizations define a breed more loosely, such that an individual may be considered of one breed as long as 75% of its parentage is of that breed. These considerations affect both pets and the show dogs entered in [[conformation show|dog shows]]. Even prize-winning [[purebred]] dogs sometimes possess crippling [[Genetic disorder|genetic defects]] due to founder effect or [[inbreeding]].<!--Pages 57 to 72, Chapter Four, "Hereditary Problems in Purebred Dogs",''The Puppy Report: How to Select a Healthy, Happy Dog'', Larry Shook, Ballantine, 1995, mass market paperback, 130 pages, ISBN 0345384393—> These problems are not limited to [[purebred]] dogs and can affect mixed-breed populations. <!--Larry Shook, the author of ''The Puppy Report: How to Select a Healthy, Happy Dog'', Pages 13 to 34, Chapter Two, "Breeders Can Hazardous to Health",''The Puppy Report: How to Select a Healthy, Happy Dog'', Larry Shook, Ballantine, 1995, mass market paperback, 130 pages, ISBN 0345384393—> The behavior and appearance of a dog of a particular breed can be predicted fairly accurately, while mixed-breed dogs show a broader range of innovative appearance and behavior.
 
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In February 2004, the Canine Studies Institute in [[Aurora, Ohio]], arranged recognized breeds of dogs into ten categories.
 
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−
[[Mixed-breed dog]]s or [[Mongrel]]s are dogs that do not belong to specific breeds, being mixtures of two or more in variant percentages. Mixed breeds, or dogs with no purebred ancestry, are not inherently "better" or "worse" than purebred dogs as companions, [[pet]]s, [[working dog]]s, or competitors in [[dog sports]]. Sometimes mixed-breed dogs are deliberately bred, for example, the Cockapoo, a mixture of Cocker Spaniel and Miniature [[Poodle]]. Such deliberate crosses may display [[hybrid vigor]] and other desirable traits, but can also lack one or more of the desired traits of their parents, such as temperament or a particular color or coat. However, without genetic testing of the parents, the crosses can sometimes end up inheriting genetic defects that occur in both parental breeds. Deliberately crossing two or more breeds is also a manner of establishing new breeds.
 
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−
===Neoteny in the rapid evolution of diverse dog breeds===
 
−
This rapid evolution of dogs from wolves is an example of [[neoteny]] or [[pedomorphosis|paedomorphism]]. As with many species, the young wolves are more social and less [[dominant]] than adults; therefore, the selection for these characteristics, whether deliberate or inadvertent, is more likely to result in a simple retention of juvenile characteristics into adulthood than to generate a complex of independent new changes in behavior. This is true of many domesticated animals, including human beings themselves, who have many characteristics similar to young [[bonobo]]. This paedomorphic selection naturally results in a retention of juvenile physical characteristics as well. Compared to wolves, many adult dog breeds retain such juvenile characteristics as soft fuzzy fur, round torsos, large heads and eyes, ears that hang down rather than stand erect, etc.; characteristics which are shared by most juvenile [[mammal]]s, and therefore generally elicit some degree of protective and nurturing behavior cross-species from most adult mammals, including humans, who term such characteristics "cute" or "appealing".
 
−
 
 
−
The example of canine neoteny goes even further, in that the various breeds are differently neotenized according to the type of behavior that was selected.
 
−
* [[Livestock guardian dog]]s retain the most juvenile characteristics: they stay close to home with their foster "litter" (which might include a flock of [[domestic sheep|sheep]]), rather than going out hunting, they have almost no predatory behavior (which would be disastrous in the vicinity of such a natural prey stimulus as sheep), they respond to perceived threats with a lot of vocalization and attempts to alert and engage the dominant individuals in their "pack" (''i.e.'' humans) whenever possible, engaging in actual combat only as a last resort. In addition, they retain very juvenile physical characteristics such as round bodies and heads, soft coats, ears that hang down, and so on, which do not elicit fear responses from the sheep in the way that an appearance similar to that of an adult wolf would. (Compare to the physical appearance of the [[border collie]], a sheep [[herding]] dog, whose physical configuration is closer to that of an adult wild canine and who therefore has a greater capacity to frighten sheep into a desired pattern of movement, along with the more adult aggressive temperament to do so).
 
−
* [[Gun dog]] breeds used in hunting&mdash;that is, [[pointer (dog)|pointers]], [[setter]]s, [[spaniel]]s, and [[retriever]]s&mdash;have an intermediate degree of paedomorphism; they are at the point where they share in the pack's hunting behavior, but are still in a junior role, not participating in the actual attack. They identify potential prey and freeze into immobility, for instance, but refrain from then stalking the prey as an adult predator would do next; this results in the "pointing" behavior for which such dogs are bred. Similarly, they seize dead or wounded prey and bring it back to the "pack", even though they did not attack it themselves, that is, "retrieving" behavior. Their physical characteristics are closer to that of the mature wild canine than the sheepdog breeds, but they typically do not have erect ears, etc.
 
−
* [[Scenthound]]s maintain an intermediate body type and behavior pattern that causes them to actually pursue prey by tracking their scent, but tend to refrain from actual individual attacks in favor of vocally summoning the pack leaders (in this case, humans) to do the job. They often have a characteristic vocalization called a bay. Some examples are the Beagle, Bloodhound, Basset Hound, Coonhound, Dachshund, Fox Hound, Otter Hound, and Harrier.
 
−
* [[Sighthound]]s, who pursue and attack perceived prey on sight, maintain the mature canine size and some features, such as narrow chest and lean bodies, but have largely lost the erect ears of the wolf and thick double layered coats.  Some examples are the Afghan, Borzoi, Saluki, Sloughi, Pharaoh Hound, Azawakh, Whippet, and Greyhound.
 
−
* [[Mastiff]]-types are large dogs, both tall and massive with barrel-like chests, large bones, and thick skulls.  They have traditionally been bred for war, protection, and guardian work.
 
−
* [[Bulldog]]-types are medium sized dogs bred for combat against both wild and domesticated animals.  These dogs have a massive, square skull and large bones with an extremely muscular build and broad shoulders.
 
−
* [[Terrier]]s similarly have adult aggressive behavior, famously coupled with a lack of juvenile submission, and display correspondingly adult physical features such as erect ears, although many breeds have also been selected for size and sometimes [[achondroplasia|dwarfed legs]] to enable them to pursue prey in their burrows.
 
−
 
 
−
The least paedomorphic behavior pattern may be that of the [[basenji]], bred in [[Africa]] to hunt alongside humans almost on a peer basis; this breed is often described as highly independent, neither needing nor appreciating a great deal of human attention or nurturing, often described as "catlike" in its behavior. It too has the body plan of an adult canine predator.
 
−
Of course, dogs in general possess a significant ability to modify their behavior according to experience, including adapting to the behavior of their "pack leaders"&mdash;again, humans. This allows them to be trained to behave in a way that is not specifically the most natural to their breed; nevertheless, the accumulated experience of thousands of years shows that some combinations of nature and nurture are quite daunting, for instance, training [[whippet]]s to guard flocks of sheep.
 
  
−
===Breed popularity===
+
==Environmental and health concerns==
−
Breed popularity varies widely over time[http://www.slate.com/id/2122298/] and in different parts of the world and different segments of the population. Counting by [[AKC]] registration (not by [[dog licence|licensing registration]] or by [[United Kennel Club|UKC]] registration, which could present different statistics), the [[Labrador Retriever]] has been the United States's most commonly registered breed of dog since 1991[http://www.akc.org/news/index.cfm?article_id=2389]. However, even within parts of the United States, popularity varies; for example, in 2005 the most-registered breed in New York City was the [[Poodle]]; the [[Yorkshire Terrier]] was the second-most-registered breed in [[Houston]] but didn't even make the top ten in [[Honolulu]][http://www.akc.org/reg/topdogsbycity.cfm]. However, animal shelters in many parts of the United States report that the most-commonly available dog for adoption is the [[American Pit Bull Terrier]] or pit bull-type mixes, making up as much as 20 percent of dogs available for adoption, none of which would be registered with the AKC.[http://www.aspca.org/site/PageServer?pagename=cruelty_pitbull] Two decades ago, in 1983, the AKC's top two registered breeds were the [[American Cocker Spaniel]] and the [[Poodle]].<ref>{{cite book|title=World Almanac and Book of Facts|year=1985|publisher=Newspaper Enterprise Association (Doubleday)}}</ref>
+
Despite the many benefits which dogs provide for humans, they also do harm. Dogs sometimes attack and bite humans. In the United States, there are about 7,000 dog attacks per year (Voelker 1986).
  
−
In [[Britain]], [[The Kennel Club]] reports that the most-registered breed from at least 1999 to 2005 was the Labrador Retriever. It rounds out the top three for 1999 to 2005 with the [[German Shepherd Dog]], also popular in the States, and the [[English Cocker Spaniel]][http://www.the-kennel-club.org.uk/pressoffice/press_top20.html], which is no longer even in the top ten in the States.
+
An even more serious problem is [[rabies]], a [[Virus|viral]] [[disease]] that is spread by animal bites. Rabies is always fatal unless treated. The [[World Health Organization]] estimates that about 55,000 people die of rabies each year; mostly in the rural areas of Africa and Asia, and mostly because of dog bites.  In Europe and North America, where most dogs are [[Immunization|immunized]] against rabies, wild animal bites are the most common cause. About 10 million people each year are treated for possible exposure to rabies (WHO 2006). Rabies is an especially serious problem in [[India]], which has about 25 million feral dogs (Sandeep 2002).
  
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==See also==
+
Dogs can also have a negative effect on the natural environment. In [[New Zealand]], pet dogs allowed to run wild were found to be a serious threat to [[kiwi]]s and other ground nesting birds (ISSG 2007). A study in the city of [[Baltimore]] in the United States done in the 1970s found that about half the dogs in the city were at least partly free ranging and that they also feed on ground nesting birds, although their main food source was garbage (Nowak 1983). In Africa, diseases spread by domestic dogs have contributed to the decline of endangered wild predators, such as the [[lion]], the [[leopard]], and the [[African hunting dog]] (Kruuk 2002).
−
* [[bark (dog)]]
 
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* [[Dog communication]]
 
−
* [[Dog licence]]
 
−
* [[List of dog breeds]]
 
  
−
==References and further reading==
+
==Dogs in culture and religion==
−
<references/><!-- ack, this is supposed to pull in items in "<" ref ">" brackets embedded in article?? —>
+
[[Image:Hercules capturing Cerberus.jpg|thumb|''Hercules capturing Cerberus'', Engraving by Sebald Beham 1540]]
−
* Abrantes, Roger (1999). ''Dogs Home Alone''. Wakan Tanka, 46 pages. ISBN 0966048423 (paperback).
+
[[Image:St Rochus.jpg|thumb|right|Statue of St Roch with his dog, in Prague, [[Czech Republic]]]]
−
* <sup>1</sup>A&E Television Networks (1998). ''Big Dogs, Little Dogs: The companion volume to the A&E special presentation'', A Lookout Book, GT Publishing. ISBN 1-57719-353-9 (hardcover).
+
Dogs have often appeared in art since the time of ancient [[Egypt]], where they were often included in hunting scenes painted within the tombs of important people. In [[Renaissance]] Europe, portraits often included a favorite lap dog.
−
* <sup>2</sup>Alderton, David (1984). ''The Dog'', Chartwell Books. ISBN 0-89009-786-0.
 
−
* Brewer, Douglas J. (2002) ''Dogs in Antiquity: Anubis to Cerberus: The Origins of the Domestic Dog'', Aris & Phillips ISBN 0856687049
 
−
*Cunliffe, Juliette (2004). ''The Encyclopedia of Dog Breeds''. Parragon Publishing. ISBN 0-75258-276-3.
 
−
* Donaldson, Jean (1997). ''The Culture Clash''. James & Kenneth Publishers. ISBN 1888047054 (paperback).
 
−
*Fogle, Bruce, DVM (2000). ''The New Encyclopedia of the Dog''. Doring Kindersley (DK). ISBN 0-7894-6130-7.
 
−
* Milani, Myrna M. (1986). ''The Body Language and Emotion of Dogs: A practical guide to the Physical and Behavioral Displays Owners and Dogs Exchange and How to Use Them to Create a Lasting Bond'', William Morrow, 283 pages. ISBN 0688128416 (trade paperback).
 
−
* Pfaffenberger, Clare (1971). ''New Knowledge of Dog Behavior''. Wiley, ISBN 0876057040 (hardcover); Dogwise Publications, 2001, 208 pages, ISBN 1929242042 (paperback).
 
−
* Savolainen, P. et al. (2002). Genetic Evidence for an East Asian Origin of Domestic Dogs. ''Science'' '''298'''. 5598: 1610&ndash;1613.
 
−
* Shook, Larry (1995). "Breeders Can Hazardous to Health", ''The Puppy Report: How to Select a Healthy, Happy Dog'', Chapter Two, pp. 13&ndash;34. Ballantine, 130 pages, ISBN 0345384393 (mass market paperback); Globe Pequot, 1992, ISBN 1558211403 (hardcover; this is much cheaper should you buy).
 
−
* Shook, Larry (1995). ''The Puppy Report: How to Select a Healthy, Happy Dog'', Chapter Four, "Hereditary Problems in Purebred Dogs", pp. 57&ndash;72. Ballantine, 130 pages, ISBN 0345384393 (mass market paperback); Globe Pequot, 1992, ISBN 1558211403 (hardcover; this is much cheaper should you buy).
 
−
* Thomas, Elizabeth Marshall (1993). ''The Hidden Life of Dogs'' (hardcover), A Peter Davison Book, Houghton Mifflin. ISBN 0395669588.
 
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* Verginelli, F. et al. (2005). Mitochondrial DNA from Prehistoric Canids Highlights Relationships Between Dogs and South-East European Wolves. ''Mol. Biol. Evol.'' '''22''': 2541&ndash;2551.
 
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* {{note|vila}}Vilà, C. et al. (1997). [http://www.mnh.si.edu/GeneticsLab/StaffPage/MaldonadoJ/PublicationsCV/Science_Dog_Paper.pdf Multiple and ancient origins of the domestic dog.] ''Science'' '''276''':1687&ndash;1689. (Also
 
−
[http://www.idir.net/~wolf2dog/wayne1.htm "Multiple and Ancient Origins of the Domestic Dog"])
 
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*{{note|Nelson}} ''Small animal internal medicine'', RW Nelson, Couto page 107
 
  
−
==External links==
+
Compared to some other animals, dogs have not played such an important role in [[religion]]. In [[Greek mythology]], the underworld was guarded by a three-headed dog named [[Cerberus]], who was later captured by [[Hercules]]. In [[Judaism]], the dog is considered an unclean animal and when they are mentioned in the Bible they are almost always portrayed in an unfavorable light. [[Islam]] also looks on dogs unfavorably. [[Mohammad]] expressed that the company of dogs voids a portion of a Muslim’s good deeds (Malik Ibn Anas 2:969).  
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{{sisterlinks|Dog}}
 
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{{Wikispecies}}
 
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;General info
 
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*[http://soc.hfac.uh.edu/artman/publish/article_145.shtml World Internet News] WIN chronicles what happens to abandoned dogs.
 
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*[http://news.nationalgeographic.com/news/2004/02/0209_040209_dogsdogsdogs.html National Geographic News] Many articles and photos about dogs
 
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*[http://rack1.ul.cs.cmu.edu/is/dogs/ Dogs and All About Them] Online, free to read and search, 1910 book about dog breeds.
 
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*[http://www.antiquebooks.net/cgi-bin/bookfront?book=27&cookie=no&userid=1103194709a Little Golden Book of Dogs] Child's book about dogs online, free to read.
 
  
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;Genetics and origins
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In [[Christianity]], [[Jesus]] told the story of the poor man [[Lazarus]], whose sores were licked by street dogs. This has traditionally been seen as showing Lazarus's wretched situation. However, some modern commentators have pointed out that the dogs' saliva could have beneficial effects on the sores and that this could be seen as an example of the dogs' unconditional love (Kilcommons 1996).
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*Lindblad-Toh, K., et. al. [http://www.nature.com/nature/journal/v438/n7069/abs/nature04338.html "Genome sequence, comparative analysis, and haplotype structure of the domestic dog"] ''Nature'' 438:803-819, December 2005.
 
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*[http://www.fiu.edu/~milesk/Genetics.htm Canid Genetics]
 
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*[http://www.nhgri.nih.gov/11008069 "Dog Genome Sequencing"] - [[National Human Genome Research Institute|NHGRI]]
 
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*[http://www.ananova.com/news/story/sm_713600.html "World's dogs are descended from Asian wolves"]
 
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*[http://magma.nationalgeographic.com/ngm/data/2002/01/01/html/ft_20020101.1.html#know "From Wolf to Woof - The Evolution of Dogs"]
 
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*[http://www.kc.net/~wolf2dog/wayne2.htm Molecular evolution of the dog family]
 
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*[http://mendel.berkeley.edu/dog.html Dog Genome Project!]
 
  
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;Training and behavior
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The [[Catholic Church]] recognizes Saint Roch (also called Saint Rocco), who lived in the early 1300s in France, as the patron saint of dogs. It is said that he caught the black plague while doing charitable work and went into the forest expecting to die. There he was befriended by a dog which licked his sores and brought him food and he was able to recover. August 16 is celebrated as the feast day of Saint Roch (Cultural Catholic 2007).
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*[http://www.uwsp.edu/psych/dog/dog.htm Noncommercial site sponsored by the University of Wisconsin-Stevens Point]
 
  
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;Breed listings from major [[kennel club]]s
+
Dogs have often been mentioned favorably in literature.  In [[Homer]]'s ''Odyssey'' (written around 800 to 600 B.C.E.) the hero's dog Argos is the only one to recognize him on his return home in disguise. One of the greatest tributes to a dog was by the English poet [[Lord Byron|Byron]] (1788-1824), who wrote of the Newfoundland, Boatswain (Byron 1808):
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*[http://www.canelupodisaarloos.com Cane lupo di Saarloos]
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:"…Beauty without Vanity,
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*[http://www.akc.org/ American Kennel Club]
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:Strength without Insolence,
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*[http://www.ankc.aust.com/breed_list.html Australian National Kennel Club]
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:Courage without Ferocity,
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*[http://www.ckc.ca/ Canadian Kennel Club]
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:and all the Virtues of Man,
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*[http://www.fci.be FCI] Fédération Cynologique Internationale - FCI
+
:without his Vices."
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*[http://www.dogdomain.com/fci-1.htm FCI] International breed standards
 
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*[http://www.the-kennel-club.org.uk The Kennel Club (UK)]
 
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*[http://www.nzkc.org.nz/dogselect.html New Zealand Kennel Club]
 
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*[http://www.ukcdogs.com/breeds/ United Kennel Club] Breed lists for many breeds and types not recognized by the AKC—and for many that are (U.S.)]
 
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*[http://mayanser.com German Shepherd Dogs]
 
  
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;Other information
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==References==
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*[http://www.abka.com/ ABKA]Your Source For All Pet Care Services
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* Alderton, D. 1984. ''The Dog''. London: Chartwell Books. ISBN 0890097860
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*[http://www.avma.org/ American Veterinary Medical Association]
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* American Kennel Club (AKC). 2006. ''The Complete Dog Book''. New York: Ballantine Books. ISBN 0345476263
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*[http://www.aahanet.org/ American Animal Hospital Association]
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* American Society for the Prevention of Cruelty to Animals (ASPCA). 2014. [https://www.aspca.org/pet-care/top-10-reasons-spay-or-neuter-your-pet Top 10 reasons to spay or neuter your pet]. ''ASPCA''. Retrieved December 18, 2014.
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<!— interwiki -->
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* American Veterinary Medical Association (AVMA). 2002. [http://www.avma.org/reference/marketstats/ownership.asp Market research statistics: Cat and dog ownership]. ''AVMA''. Retrieved August 6, 2007.
 +
* Byron, G. G. 1808. [http://www.poetryloverspage.com/poets/byron/byron_ind.html Epitaph to a dog]. ''Poetry Lovers Page''. Retrieved August 2, 2007.
 +
* Clutton-Brook, J. 1999. ''A Natural History of Domesticated Mammals.'' Cambridge, UK: Cambridge University Press. ISBN 0521634954
 +
* Cultural Catholic LLC. 2007. [http://www.culturalcatholic.com/SaintRoch.htm Saint Roch]. ''Cultural Catholic''. Retrieved August 8, 2007.
 +
* Davis, J. 1998. [http://www.uwsp.edu/psych/dog/LA/davis2.htm Color and acuity differences between dogs and humans]. University of Wisconsin, Stevens Point. Retrieved August 2, 2007.
 +
* Humane Society of the United States (HSUS). 2007. [http://www.hsus.org/animals_in_research/species_used_in_research/dog.html Animals used in research: Dog profile]. ''Human Society of the United States''. Retrieved August 6, 2007.
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* Invasive Species Specialist Group (ISSG). 2007. [http://www.issg.org/database/species/ecology.asp?si=146&fr=1&sts=sss ''Canis lupus'' (mammal)]. ''Invasive Species Specialist Group''. Retrieved August 8, 2007.
 +
* Killcommons, B., and M. Capuzzo. 1996. ''Mutts: America's Dogs''. New York: Time Warner. ISBN 0446519499
 +
* Kruuk, H. 2002. ''Hunter and Hunted: Relationships Between Carnivores and People.''  Cambridge, UK: Cambridge University Press. ISBN 0521814103
 +
* Malik Ibn Anas, al-Muwatta’ (Egypt: al-Babi al-Halabi, n.d.), 2:969. Reported in El Fadl
 +
* McGourty, C. 2002. [http://news.bbc.co.uk/2/hi/science/nature/2498669.stm Origin of dogs traced]. ''BBC News''. Retrieved July 23, 2007.
 +
*Nelson, R. W., and C. G. Couto. 2003. ''Small Animal Internal Medicine, Third Edition''. Philadelphia: Mosby. ISBN 032301724X
 +
* Nowak, R. M., and J. L. Paradiso. 1983. ''Walker's Mammals of the World''. Baltimore: The Johns Hopkins University Press. ISBN 0801825253
 +
* Sandeep, K. 2002. Man's worst enemy. ''The Hindu''.
 +
* Savolainen, P.,  Y. Zhang, et al. [http://adsabs.harvard.edu/abs/2002Sci...298.1610S Genetic evidence for an East Asian origin of domestic dogs]. ''Science''. Retrieved July 24, 2007.
 +
* Voelker, W. 1986. ''The Natural History of Living Mammals''. Medford, New Jersey: Plexus Publishing. ISBN 0937548081
 +
*  Wayne, R. K., C. Vila, et al.  1997. [http://www.mnh.si.edu/GeneticsLab/StaffPage/MaldonadoJ/PublicationsCV/Science_Dog_Paper.pdf Multiple and ancient origins of the domestic dog]. ''Science''. June 13, 1997. Retrieved July 24, 2007.
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* World Health Organization (WHO). 2006. [http://www.who.int/mediacentre/factsheets/fs099/en/ Rabies]. ''World Health Organization''. Retrieved August 8, 2007.
  
  
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{{Credit8|Dog|138982039|Disc_dog|147147444|Sheepdog_trial|122079811|Earthdog_trial|145340673|Field_trial|135006059|Obedience_trial|149131153|Tracking_trial|139330271|Flyball|141312739}}
 
[[Category:Life sciences]]
 
[[Category:Life sciences]]
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[[Category:Animals]]
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[[Category:Mammals]]
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[[Category:Carnivores]]

Latest revision as of 11:04, 2 August 2023

Domestic dog
Fossil range: Late Pleistocene - Recent
other images of dogs
Conservation status
Conservation status: Domesticated
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Canidae
Genus: Canis
Species: C. lupus
Subspecies: C. l. familiaris
Trinomial name
Canis lupus familiaris

The dog (Canis lupus familiaris or Canis familiaris) is usually considered to be humankind's first, and perhaps most important, domestic animal. It generally is classified as a subspecies of the gray wolf (Canis lupus), a mammal of the Canidae family of the order Carnivora.

The word "dog" also is used to refer to some other members of the Canidae family, for instance the bush dog (Speothos venaticus) of South America and the raccoon dog (Nyctereutes procyonoides) of Asia. The family Canidae itself often is called the "dog family" and includes jackals and coyotes, which are closely related to dogs and wolves, as well as foxes, which are less closely related. Members of the Canidae family are called "canids."

The trainability, devotion, playfulness, and ability to fit into human households have earned dogs a unique position in the realm of interspecies relationships. Dogs have lived and worked with humans in so many roles—hunting, herding and protecting sheep and cattle, guarding people and property, rescuing people, companionship, and so forth—that their loyalty has earned them the unique sobriquet, "man's best friend." Their actions mimic the human idea of love and friendship, leading many dog owners to view their pets as family members.

In a process generally thought to span at least 14,000 years, humans have domesticated the dog, produced innumerable breeds, and bred and trained them to perform a great variety of useful services and sometimes dubious actions, including as guard dogs trained to instill fear in people and as sports dogs taught to fight other dogs to the death.

Lateral view of a dog's bone structure.

Characteristics

Dogs, like wolves and other canids, are specialized for a life of hunting and eating other animals. Their bodies are compact and muscular and their legs are long, which gives them speed and endurance for chasing prey. Their jaws are large and their teeth are well suited for grasping, biting, and tearing flesh. Their digestive systems, however, are suited for some plant foods as well as flesh.

Most dogs are covered with a thick coat of fur, which protects them from the elements. Alaskan malamutes and Siberian huskies, which originated in the Arctic, are able to live outside without shelter in temperatures far below freezing. Dogs' coats come in a wide range of colors, including black, white, brown, yellow, red, and gray. They come in a range of lengths and textures from very short to long, either straight or curly (AKC 2006).

A dog's heart and lungs are oversized relative to its body and its normal everyday needs. A dog also has relatively more red blood cells than a human. Most of the time the dog will keep the extra red blood cells stored in its spleen. When the animal enters into a situation where its full metabolism is required, such as play, catching game, or fighting other dogs, the extra cells are released into the bloodstream. The "oversized" heart and lungs would then be running at full capacity, and the animal would have an enhanced ability to engage in aerobic activity. This activity produces internal heat. Dogs, being covered in fur, are limited in their ability to cool down. After a short time the animal must either cease its athletic activity or risk harming itself from overheating. One can easily observe this pattern of intense activity followed by rest periods in puppies. During the rest phase, the spleen collects red blood cells and the animal may pant to cool down.

Dogs, like most carnivores, are naturally active only 4 to 6 hours each day and prefer to sleep the rest of the time (Kruuk 2002).

Dogs, like other canids, are considered to be among the most intelligent of all animals, as shown by their ability to adapt to changing conditions in human society.

The dog's ancestor, the gray wolf, is the largest canid; with adults weighing between 18 and 80 kg (40 to 175 lbs). Modern dogs can weigh anywhere from 1 to over 100 kg (2.2 to 220 lbs). Dingos, wild dogs of Australia which are descended from domestic dogs, average 10 to 20 kg (22 to 44 lbs) in weight (Nowak 1983).

Senses

Sight

In general, the vision of dogs is not as good as that of humans. They have only limited color vision, equivalent to red-green color blindness in humans (Alderton 1984). They also are nearsighted compared to humans and can not see detail as well. The average dog's vision seems to be about 20/50 to 20/100, using the human standard. On the other hand they see better in dim light and may also detect motion better than humans (Davis 1998).

Hearing

This mixed-breed dog angles her ears to find the source of a sound.

The hearing of dogs is superior to humans. They can detect sounds that are lower and those that are higher in frequency. They also have a degree of ear mobility that helps them to rapidly pinpoint the exact location of a sound. Eighteen or more muscles can tilt, rotate, and raise or lower a dog's ear. Additionally, a dog can identify a sound's location much faster than a human can, as well as hear sounds up to four times the distance that humans are able to. Those with more natural ear shapes, like those of wild canids, generally hear better than those with the floppy ears of many domesticated species.

Smell

Scent hounds, especially the Bloodhound, are known for their keen sense of smell

Dogs have nearly 220 million smell-sensitive cells over an area about the size of a pocket handkerchief (compared to 5 million over an area the size of a postage stamp for humans). Some breeds have been selectively bred for excellence in detecting scents, even compared to their canine brethren.

What information a dog actually detects when it is scenting is not perfectly understood. Although once a matter of debate, it now seems to be well established that dogs can distinguish two different types of scents when trailing: An air scent from some person or thing that has recently passed by, as well as a ground scent that remains detectable for a much longer period. The characteristics and behavior of these two types of scent trail would seem, after some thought, to be quite different, the air scent being intermittent but perhaps less obscured by competing scents, whereas the ground scent would be relatively permanent with respect to careful and repetitive search by the dog, but would seem to be much more contaminated with other scents. In any event, it is established by those who train tracking dogs that it is impossible to teach the dog how to track any better than it does naturally; the object instead is to motivate it properly, and teach it to maintain focus on a single track and ignore any others that might otherwise seem of greater interest to an untrained dog. An intensive search for a scent, for instance searching a ship for contraband, can actually be very fatiguing for a dog, and the dog must be motivated to continue this hard work for a long period of time.

Reproduction

A Catahoula leopard dog mother nursing her litter of puppies.

In domestic dogs, sexual maturity (puberty) begins to happen around age 6 to 12 months for both males and females, although this can be delayed until up to two years old for some large breeds. Adolescence for most domestic dogs is around 12 to 15 months, beyond which they are for the most part more adult than puppy. As with other domesticated species, domestication has selectively bred for higher libido and earlier and more frequent breeding cycles in dogs than in their wild ancestors.

Dogs bear their litters roughly 9 weeks after fertilization, although the length of gestation can vary from 56 to 72 days. A general rule of thumb is that a mammal will produce half as many offspring as the number of teats on the mother. This rule is altered in domesticated animals since larger litters are often favored for economic reasons and in dogs, particularly, the great range of sizes and shapes plays a role in how many healthy puppies a female can carry. An average litter consists of about six puppies, though this number may vary widely based on the breed of dog. Small dogs generally produce from one to four puppies in each litter, while much larger breeds may average as many as 12 pups in each litter. The number of puppies also varies with the mother's age and health, the father's sperm count, the timing of the breeding, and many other factors.

Lifespan

The typical lifespan of dogs varies considerably by breed. For example, many giant dog breeds (such as great danes) average only 7 or 8 years, while some small terrier breeds, or toy breeds, might live to be older than 20. The average lifespan for mixed-breed and midsize dogs is about 13 to 14 years. The longest-lived dog with reliable documentation died at 29 years and 27 days; the breed of the dog was an Australian cattle dog and it lived in Virginia, United States, with the date of death in 1939. Although the lifespans of all living species are mostly uncontrollable, one can significantly extend a dog's life by feeding it the right kinds of foods, giving it regular exercise, treating its diseases, caring for its special needs, and giving it love and comfort.

Social behavior

Dogs, like almost all canids, are social animals. Wolves, and it is assumed the ancestors of dogs, almost always live in pairs, a male and a female with their young, or in larger groups called packs. Within the pack, the individual animals communicate with each other by visual signals, such as body and facial expressions and tail wagging, as well as by vocal signals, such as growls and howls. Pack members sometimes hunt individually and sometimes as a group, depending on the situation, including the size of the prey (Kruuk 2002).

The members of the pack cooperate in many activities, such as hunting, caring for the young, and defending their territory from intruders. Within each pack, there is a dominant pair which takes the lead, while the others support them. In most cases, only the dominant pair reproduces. Wolves struggle to establish dominance and sometimes fight with each other, but this seldom leads to serious injury or death since the losing animal will display submissive behavior which discourages further attacks. Studies of feral dogs have found that they often form packs of 3 to 5 individuals (Clutton-Brook 1999; Nowak 1993; Voelker 1986).

Origins

According to recent genetic research, the lineage of dogs separated from that of wolves about 100,000 years ago (Wayne 1997). It is not known when the ancestors of dogs began to associate with humans. The first fossil evidence of domesticated dogs, which had changed in physical form from their wolf ancestors, dates from around 15,000 years ago. Dog fossils from about this time have been found in Asia, Europe, North America, and South America (Clutton-Brock 1999).

Other genetic research seems to indicate that China was the site of the original domestication of dogs (McGourty 2002). Genetic research has identified 14 ancient dog breeds, with the oldest being the Chow Chow, Shar Pei, Akita Inu, Shiba Inu, and Basenji. Many of the 14 breeds are associated with China and Japan (Savolainen 2002).

Human relationships

Dogs are highly social animals. This can account for their trainability, playfulness, and ability to fit into human households and social situations. This similarity has earned dogs a unique position in the realm of interspecies relationships.

The loyalty and devotion that dogs demonstrate as part of their natural instincts as pack animals closely mimics the human ideas of love and friendship, leading many dog owners to view their pets as full-fledged family members. Conversely, dogs seem to view their human companions as members of their pack, and make few, if any, distinctions between their owners and fellow dogs.

Dogs fill a variety of roles in human society and are often trained as working dogs. For dogs that do not have traditional jobs, a wide range of dog sports provide the opportunity to exhibit their natural skills. In many countries, the most common and perhaps most important role of dogs is as companions or pets. In the United States, about 36 percent of households own at least one dog, with the total number of animals about 62 million (AVMA 2002).

Dogs have lived and worked with humans in so many roles that their loyalty has earned them the unique sobriquet, "man's best friend."

Terminology

The English word "dog," in common usage, refers to the domestic pet dog, Canis lupus familiaris. The species was originally classified as Canis familiaris by Linnaeus in 1758. In 1993, dogs were reclassified as a subspecies of the gray wolf, Canis lupus, by the Smithsonian Institution and the American Society of Mammalogists.

The English word "dog" might derive from the Old English "docga," a "powerful breed of canine," like the modern mastiff. The English word "hound" is a cognate of German Hund, Dutch hond, common Scandinavian hund, Icelandic hundur, which, though referring to a specific breed in English, means "dog" in general in the other Germanic languages. "Hound" itself derives from the Proto-Indo-European *kwon-, which is the direct root of the Greek κυων (kuōn) and the indirect root of the Latin canis through the variant form *kani-.

In breeding circles, a male canine is referred to as a "dog," while a female canine is called a "bitch." The father of a litter is called the "sire," and the mother of a litter is called the "dam." Offspring are generally called "pups" or "puppies" until they are about a year old. A group of offspring is a "litter." The process of birth is "whelping." Many terms are used for dogs that are not purebred.

The constellations Canes Venatici, Canis Major, and Canis Minor are named from the Latin word for "dog," for their perceived resemblance to dogs. Sirius, the brightest star in the sky as seen from earth, is called the "dog star" because it is found in Canis Major. The time when Sirius rises just before sunrise, mainly July and August, are called the "dog days of summer."

Breeds

Different breeds of dogs emerged over time due to environmental factors and human selection. In ancient Egypt, dogs looking like the modern greyhound and the mastiff are pictured in art. In ancient Roman writings, miniature pet dogs like modern toy breeds are mentioned (Clutton-Brook 1999).

There are said to be over 450 different dog breeds in the world. As of 2006, the American Kennel Club recognized 153 breeds, divided into 7 groups (AKC 2006):

  • Sporting breeds were originally bred and trained to assist gun-wielding hunters in finding and recovering birds and other small game. They include various pointers, spaniels, and retrievers.
  • Hounds were bred to track and engage larger hunted animals. They include the bloodhound, the English foxhound, and the beagle.
  • Working breeds were bred for various tasks; such as guarding people, livestock, and property; pulling sleds; and rescuing people from water or snow. They include the rotweiler, the saint bernard, and the akita.
  • Terriers were originally bred to catch and kill small animals, especially rats, without the help of a human hunter. Popular terriers include the airedale terrier and the Parson Russell terrier (also called the Jack Russell terrier).
  • Toy Breeds are smaller dogs bred to be pets. They include the pug, the pekingese, and the chihuahua.
  • Non-sporting breeds are medium-sized or large dogs bred to be pets, or in the case of the dalmation, a companion to horses. The poodle is one of the most popular non-sporting breeds.
  • Herding breeds were bred to herd sheep or cattle. They include the collie, the German shepherd, and the Old English sheepdog.

Through history different dog breeds have gone in and out of fashion. In England, the King Charles Spaniel fell out of favor in 1689 when the house of Stuart was overthrown in the Glorious Revolution and was reborn in the twentieth century as the Cavalier King Charles Spaniel. In the United States, the beagle became very popular in the 1960s because of the cartoon character Snoopy. The most popular breed in the United States today is the Labrador retriever (AKC 2006).

Mixed breed dogs

Mixed-breed dogs, such as this Australian Border Collie cross, are often desired as working animals for their robust health and intelligence.

The majority of dogs in the world are of mixed breed or no definite breed. It is estimated that 60 percent of dogs in the United States are mixed breeds, and the number it thought to be much higher in poorer countries. Advocates of mixed breed dogs as working dogs and pets say that they are more intelligent and have fewer health problems than purebreds (Kilcommons 1996).

Working, utility, and assistance dogs

Labrador retrievers are often used as assistance dogs.
Belgian Malinois war dog.

The first ways that dogs were useful to humans were as helpers in hunting and as protectors. These roles grew out of the dogs' natural instincts. As time went on, dogs were trained to perform other tasks and were specially breed to do so. Some of the modern types of working dogs are:

  • Assistance dogs help the seeing and hearing-impaired. Others are trained to help those with epilepsy and psychiatric disorders, by detecting the onset of the condition so they can seek help. The typical assistance dog is a sociable breed such as a Labrador retriever. In the United States, people with assistance dogs are guaranteed access to public places by law.
  • Detection dogs are trained to, and work at, using their senses (almost always the sense of smell) to detect substances such as explosives or illegal drugs.
  • Guard dogs are trained to protect people and property. These are commonly doberman pinschers, German shepherds, and rottweilers, or mixes of these breeds. Guard dogs differ from watch dogs in that they are expected to engage an intruder, while watch dogs are only expected to bark to alert the property owner.
  • Herding dogs are trained to control livestock in the range. Sheepdogs and collies are common breeds.
  • Hunting dogs search for and retrieve game. Pointers and retrievers are typical hunting breeds.
  • Police dogs, typically German shepherds, are trained to assist law enforcement officers, often apprehending fleeing suspects. Schutzhund is a special test developed in Germany in the early 1900s to test if a German shepherd has the right talents and temperment to be successfully trained as a police dog.
  • Rescue dogs are those that search for missing humans. The archetypal breeds are the Saint Bernard and the bloodhound, although any dog with a good sense of smell can be trained to perform this task. One of the most famous dog rescues in history is that of Napoleon Bonaparte, a poor swimmer, who fell into the ocean one night in 1814, and was rescued by a Newfoundland.
  • Show dogs do tricks for the entertainment of audiences. Poodles and American Eskimo dogs were very popular as show dogs in circuses and traveling shows in the past. Now many types of dog perform in movies and television.
  • Therapy dogs, with friendly and gentle temperaments, are trained to provide comfort and affection to hospitalized and institutionalized patients. The modern concept of the therapy dog was begun in 1976 by Elaine Smith, an American nurse.
  • War dogs are used by the military to detect mines and enemy soldiers. War dogs, looking much like modern mastiffs, are pictured in ancient Assyrian art. Dogs continued to be used in war through Roman and Medieval times. In 1560, Queen Elizabeth I of England sent 8,000 war dogs, equipped with spiked collars and coats of mail, with her army sent to Ireland to suppress a rebellion (Kilcommons 1996). In World War II, the Soviet army trained dogs to carry explosives and run under enemy tanks, blowing them up.

Show and sport (competition) dogs

An English Springer spaniel in a dog show
The border collie uses a direct stare at sheep, known as "the eye," to intimidate while herding at a trial.

Owners of dogs often enter them in competitions, whether show (breed conformation shows) or sports, including dog racing and dog sledding. The winners garner both prestige and prize money. These dogs are often bred specifically for competition, which may not be entirely beneficial for the breeds, due to the magnification of hereditary defects.

  • Dog agility is a sport in which dogs complete a timed obstacle course. It is a fairly new sport, started in 1978 in the United Kingdom.
  • Tracking trials encourage dogs to make use of their strongest facility by emulating the finding of a lost person or article in a situation where the performance of the dog can be fairly assessed. Because of this, the tracks laid are not the wanderings, which may characterize a lost person, nor do they include deliberate attempts by the tracklayer to deceive the following dog.
  • Dogsled racing is a winter sport where a team of dogs pull a sled and driver (called a musher). The Iditarod Trail Sled Dog Race is perhaps the most famous of these races. Dog sledding is an ancient form of transportation and still a very effective way of moving freight across this type of terrain. Most modern dog sledders use mixed breed dogs.
  • Dog racing, almost always emphasizing greyhounds, involves dogs racing at betting tracks in a sport not unlike horse racing, reaching speeds of 40 miles per hour. Elsewhere, dachshunds are often raced, as a humorous sidelight in charity events.
  • Dog fighting and dog baiting are blood sports involving dogs. In the past, they were very popular but now they are illegal in most jurisdictions, but are still occasionally performed underground. Some of the breeds which have been used in dog fighting are the akita, the Irish terrier, and the American pit bull terrier (often called the pit bull).
  • Disc dog is the more generic name for what is commonly called Frisbee dog. In disc dog competitions, dogs and their human disc throwers compete in events such as distance catching and somewhat choreographed freestyle catching. The sport celebrates the bond between handler and dog, by allowing them to work together. The term "disc" is preferred because "Frisbee" is a trademark (held by Wham-O) for a brand of flying disc.
  • Flyball is an event in which teams of dogs race against each other from a start/finish line, over a line of hurdles, to a box that releases a tennis ball to be caught when the dog presses the spring loaded pad, then back to their handlers while carrying the ball. Flyball has become popular because it is a sport in which all sizes and breeds of dog can compete.
  • Sheepdog trials (or simply dog trials) are competitive events in which herding dog breeds move sheep around a field, fences, gates, or enclosures as directed by their handlers. Such events are particularly associated with hill farming areas, where sheep range widely on largely unfenced land. These trials are popular in the United Kingdom, Ireland, South Africa, Canada, the United States, Australia, New Zealand, and other farming nations. Some venues allow only dogs of known herding breeds to compete; others allow any dog that has been trained to herd.
  • Earthdog trials test dachshunds and small terriers for their working abilities and instinct. Earthdog den trials involve underground tunnels that dogs must negotiate, while scenting a rat, the "quarry." The dog must follow the scent to the quarry and then "work" the quarry. Depending on the sanctioning organization, “working” means barking, scratching, staring, pawing or such at it, although the quarry is protected at all times.
  • Field trials are highly competitive events at which hunting dogs compete against one another. Field trials are organized by kennel clubs or other gun dog organizations.
  • Obedience trials are events in which a dog must perfectly execute a predefined set of tasks when directed to do so by its handler. Obedience competition provides an opportunity for a person and a dog to work as a highly tuned team.
  • Dog shows involve purebreds entered in conformation dog show and evaluated by how closely they match the ideal characteristics of the breed. The Westminster Kennel Club Dog Show is one of the most famous of this type of competition.

Dogs in research

Dogs have long been used as subjects of scientific research. In the 1890s, the Russian scientist Ivan Pavlov used dogs to study psychological conditioning. Much of the research which led to the discovery of insulin and to the successful treatment of diabetes in humans was carried out using dogs as experimental subjects. On November 3, 1957, a Russian dog, Laika, became the first animal to orbit the earth.

Dogs presently make up only a small percentage of animals used in research; rats and mice far outnumber them. However, they are especially important in medical studies, for instance on the effects of drugs. Among the reasons for this are their fairly large size and their ease in being taken care of and controlled.

Beagles are especially popular for research because of their calm and friendly nature. Most research beagles are especially bred for this purpose. Other research dogs are obtained from various sources including pound seizure, newspaper ads, strays, and lost or stolen pets. Over the years there have been protests against the treatment of research dogs and laws have been passed to protect them, and in some cases to prevent former pet dogs from being used in research (HSUS 2007).

Dog health

Dogs are susceptible to various diseases, ailments, and poisons, some of which effect humans in the same way, others of which are unique to dogs.

Diet

At present, there is some debate as to whether domestic dogs should be classified as omnivores or carnivores, by diet.

The classification in the Order Carnivora does not necessarily mean that a dog's diet must be restricted to meat; unlike an obligate carnivore, such as the cat family with its shorter small intestine, a dog is dependent on neither meat-specific protein nor a very high level of protein in order to fulfill its basic dietary requirements. Dogs are able to healthily digest a variety of foods including vegetables and grains, and in fact dogs can consume a large proportion of these in their diet. Wild canines not only eat available plants to obtain essential amino acids, but also obtain nutrients from vegetable matter from the stomach and intestinal contents of their herbivorous prey, which they usually consume.

Domestic dogs can survive healthily on a reasonable and carefully designed vegetarian diet, particularly if eggs and milk products are included. Some sources suggest that a dog fed on a strict vegetarian diet may develop dilated cardiomyopathy since it lacks L-carnitine (Nelson 2003), however, maintaining a balanced diet is also a factor since L-carnitine is found naturally in many nuts, seeds, beans, vegetables, fruits, and whole grains. In the wild, dogs can survive on a vegetarian diet when animal prey is not available. However it has been noted, both by observation of extremely stressful conditions such as the Iditarod Trail Sled Dog Race and by scientific studies of similar conditions, that high-protein (approximately 40 percent) diets including meat help prevent damage to muscle tissue. (This research is also true for some other mammals.) This level of protein corresponds to the percentage of protein found in the wild dog's diet when prey is abundant; higher levels of protein seem to confer no added benefit.

Spaying and neutering

In the United States, most pet dogs are spayed or neutered. Spaying is the surgical removal of the female's ovaries and uterus. Neutering is the removal of the male's testicles. Spayed and neutered dogs avoid some diseases such as breast and testicular cancer. Behaviors such as urinating in the house, running away, and aggression are also reduced; and unwanted litters of puppies are avoided, which could contribute to the problem of stray and feral dogs (ASPCA 2014).

Diseases

Infectious diseases commonly associated with dogs include rabies (hydrophobia), canine parvovirus, and canine distemper. Congenital diseases of dogs can include a wide range from hip dysplasia and medial patellar luxation to epilepsy and pulmonic stenosis. Canines can get just about anything a human can get (excluding many infections, which are species specific) like hypothyroidism, cancer, dental disease, heart disease, Addison's disease, and so forth.

Two serious medical conditions affecting dogs are pyometra, affecting unspayed females of all types and ages, and bloat, which affects the larger breeds or deep chested dogs. Both of these are acute conditions, and can kill rapidly; owners of dogs which may be at risk should learn about such conditions as part of good animal care.

Parasites

Common external parasites are various species of fleas, ticks, and mites. Internal parasites include hookworms, tapeworms, roundworms, and heartworms.

Common physical disorders

Some breeds of dogs are also prone to certain genetic ailments, such as hip dysplasia, luxating patellas, cleft palate, blindness, or deafness. As noted, dogs are also susceptible to the same ailments that humans are, including diabetes, epilepsy, cancer, and arthritis.

Environmental and health concerns

Despite the many benefits which dogs provide for humans, they also do harm. Dogs sometimes attack and bite humans. In the United States, there are about 7,000 dog attacks per year (Voelker 1986).

An even more serious problem is rabies, a viral disease that is spread by animal bites. Rabies is always fatal unless treated. The World Health Organization estimates that about 55,000 people die of rabies each year; mostly in the rural areas of Africa and Asia, and mostly because of dog bites. In Europe and North America, where most dogs are immunized against rabies, wild animal bites are the most common cause. About 10 million people each year are treated for possible exposure to rabies (WHO 2006). Rabies is an especially serious problem in India, which has about 25 million feral dogs (Sandeep 2002).

Dogs can also have a negative effect on the natural environment. In New Zealand, pet dogs allowed to run wild were found to be a serious threat to kiwis and other ground nesting birds (ISSG 2007). A study in the city of Baltimore in the United States done in the 1970s found that about half the dogs in the city were at least partly free ranging and that they also feed on ground nesting birds, although their main food source was garbage (Nowak 1983). In Africa, diseases spread by domestic dogs have contributed to the decline of endangered wild predators, such as the lion, the leopard, and the African hunting dog (Kruuk 2002).

Dogs in culture and religion

Hercules capturing Cerberus, Engraving by Sebald Beham 1540
Statue of St Roch with his dog, in Prague, Czech Republic

Dogs have often appeared in art since the time of ancient Egypt, where they were often included in hunting scenes painted within the tombs of important people. In Renaissance Europe, portraits often included a favorite lap dog.

Compared to some other animals, dogs have not played such an important role in religion. In Greek mythology, the underworld was guarded by a three-headed dog named Cerberus, who was later captured by Hercules. In Judaism, the dog is considered an unclean animal and when they are mentioned in the Bible they are almost always portrayed in an unfavorable light. Islam also looks on dogs unfavorably. Mohammad expressed that the company of dogs voids a portion of a Muslim’s good deeds (Malik Ibn Anas 2:969).

In Christianity, Jesus told the story of the poor man Lazarus, whose sores were licked by street dogs. This has traditionally been seen as showing Lazarus's wretched situation. However, some modern commentators have pointed out that the dogs' saliva could have beneficial effects on the sores and that this could be seen as an example of the dogs' unconditional love (Kilcommons 1996).

The Catholic Church recognizes Saint Roch (also called Saint Rocco), who lived in the early 1300s in France, as the patron saint of dogs. It is said that he caught the black plague while doing charitable work and went into the forest expecting to die. There he was befriended by a dog which licked his sores and brought him food and he was able to recover. August 16 is celebrated as the feast day of Saint Roch (Cultural Catholic 2007).

Dogs have often been mentioned favorably in literature. In Homer's Odyssey (written around 800 to 600 B.C.E.) the hero's dog Argos is the only one to recognize him on his return home in disguise. One of the greatest tributes to a dog was by the English poet Byron (1788-1824), who wrote of the Newfoundland, Boatswain (Byron 1808):

"…Beauty without Vanity,
Strength without Insolence,
Courage without Ferocity,
and all the Virtues of Man,
without his Vices."

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