Dog

Domestic dog
Scientific classification
Domain: Eukaryota Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Mammalia Order: Carnivora Family: Canidae Genus: Canis Species: C. lupus Subspecies: C. l. familiaris
Trinomial name
Canis lupus familiaris

Most recent approved version of Dog

The dog is a mammal domesticated from specific wolves thousands of years ago. Throughout the world today, dogs are frequently associated with humans, and because of this the dog is often called "man's best friend". They have been used in a variety of ways, including as house pets, cherished companions, full-time workers, and even as a form of food.

Dogs and people may communicate better than any other two species. , Dogs and humans understand each other on a basic level: we are able to interpret the dog's instinctive body language (along with canine vocalizations like the growl and whine); and the dog, in turn, has an innate ability to respond appropriately both to human body language, as well as to the emotional tone of the human voice. People can be educated beyond these basics to manage their dogs more precisely, and dogs can be trained to be extremely responsive to people. (see the Training section).

Dog anatomy and health

Modern dog breeds show more variation in size, appearance, and behavior than any other domestic animal.

Physical characteristics

Dogs generally share attributes with their wild ancestors, the wolves. Dogs are both predators and scavengers, 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 wrist bones, 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.

Sight

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 dogs, the sight hounds, have been specifically bred to capitalize on their use of vision in tracking prey. These breeds include the Greyhound and Afghan Hound. The most capable sighthounds have a field of vision up to 270° (compared to 180° for humans). Broad-headed dog breeds with forward set eyes have a much narrower field of vision, sometimes no wider than the human 180 degrees.

Hearing

Dogs detect sounds as low as the 16 to 20 Hz frequency range (compared to 20 to 70 Hz for humans) and as high as 70 kHz to 100 kHz (compared to 13 to 20 kHz for humans), 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. The dog's sensitivity to even very quiet sounds, as compared to a human’s, means that a dog can identify a sound's location much faster, as well as hear sounds that are coming from far more distant sources than a human companion by its side.

Those with more open ear shapes, like the erect ears of wild canids like the fox, generally hear better than those with the floppier ears of many domesticated species.

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). It is fair to say that all dogs have a rich olfactory experience than ours. Some breeds have been selectively bred for excellence in detecting scents, over and above their canine brethren, such as the scent hounds including and particularly Bloodhounds.

Reproduction

The dog's reproductive cycle

See the main article at dog reproduction.

Bitches (female dogs) have a reproductive cycle that generally varies from six months to one year, although there are bitches that come into oestrus more or less frequently. The dam (mother) ordinarily gives birth to more than one puppy at a time.

Dog breeding

See the main article at dog breeding.

Dogs and humans in daily life

Some dog owners view their pets as fully-fledged family members, and most dogs are able to act the part. That ability stems from two basic sources: (1) the "hard-wiring" of the dog's behavior (programmed by its canine genes), and (2) the individual dog's experience with people. Dogs are like humans in being highly social animals. Although the instincts to behave in ways that ease interactions in the pack are inborn in all normal dogs, the right early experiences are critical if puppies are to grow up into companionable dogs. Those "right" experiences have everything to do with contact with people and with other dogs, and they must occur early in the dog's life - probably before the puppy reaches 12 weeks of age. In fact, that particular period of time in a puppy's life is actually called the "critical period" or "sensitive period".

Puppies are frequently born in groups known as litters

When puppies are raised with plenty of close contact to people and to other dogs, they become fully socialized. Socialized pups seem to view their human companions as members of their pack, and make few, if any, distinctions between their owners and fellow dogs. As these puppies mature, they generally learn to modify their behavior towards people, and treat their human companions more gently than their canine ones. Evidence shows that puppies who are raised without human nurturing do not fully adjust to interactions with owners once they have passed the critical period of about 3 months of age, no matter how much gentle attention is then given them. Orphaned puppies that are bottle fed and raised by humans alone, without any contact to any other dog or puppy, are in danger of becoming abnormally fixated on humans, and such puppies include animals that turn their sexual attentions, including mounting behavior, to people instead of to dogs.

The group of puppies born together is called a litter. That means that most pups are raised in a social group. However, in situations where puppies are isolated from other dogs, and are raised alone, without experiences in canine society, they can fail to learn the give and take of normal puppies. That's one reason that the dog or older puppy adopted from a shelter or obtained from a private seller can pose problems to a new owner. Brought out on a leash in streets where other dogs go by, or let off a leash in a dog park or outdoor space where other dogs are free, a poorly socialized dog may attack other dogs out of fear. Once grown, such pups most often can never be successfully integrated into a group of dogs.

The archetypical "friendly dog" apperance

Dogs fill a variety of roles in human society and are often trained as working dogs. Thousands of dogs throughout the world actively herd sheep and cattle, guard people and property, and guide the blind and disabled. Dogs are an important part of rescue work in disasters. Their noses aid police and military searches for weapons, drugs, and other contraband. However, the most common (and perhaps most important) role of dogs in many countries is as a human companion.

Dog breeds

Shar Peis are known for their characteristic wrinkles, which is one of their many attributes

Just as one individual animal might have a combination of traits that causes that particular dog to appear so different from another, there are diverse breeds of dogs, where each breed includes dogs that are very similar to each other, but distinct in some identifiable manner from the dogs of a different breed. Through the years, by concentrating particular genes and reducing other ones, breeds have developed in which each member shares a recognizable "brand" of canine style.

In kennel club terms, purebred dogs are individuals that have been selected to "breed true". That means that a good example of a pure bred (pedigreed) dog looks like its kind in physical appearance, and acts like its kind in general temperament and certain behaviors. Generally, two purebred parents of the same breed will always produce a litter of pups that will grow up to be quite like them in looks, temperament, and behavior, as opposed to resembling the types of dogs from which the breed originated. The two Chinese Shar Pei youngsters pictured at left show the famously loose and wrinkled skin of their kind, but there are many more characteristics that typify that breed, ranging from a blue-black tongue to a calm, confident stance.

Dogs have an enormous range of normal height and lean weight. The Chihuahua is the smallest of the purebreeds and the Irish Wolfhound is the largest. Despite the great differences in size between these two extremes, all dogs are the same species and can interbreed successfully, although now, thanks to human intervention and the development of dog breeds, care must be taken to only breed individual dogs that are compatible--the mating of a Chihuahua bitch (female) with a Great Dane, for example, would have disastrous consequences for the health of the female dog. Dogs also have an incredibly broad range of coat (fur) and skin colors and patterns, skull and face shape, pelage (fur) length and texture, tail shape and carriage, athletic ability and temperaments. All of these, along with other physical characteristics, are influenced by inherited genes. Even certain specific complex behaviors (like pointing, or retrieving) appear to be inherited in dogs. The gene pool of domestic dogs is highly diverse.

Registered purebreds

Presently, over 800 dog breeds are recognized by breed and kennel clubs worldwide. Dogs can be registered with a club and receive certifications (commonly called "papers") that indicate a pedigreed purebred status.

Kennel clubs and their affiliates

For more information, see the articles at breed club and kennel club

In order to qualify for registration, a purebred puppy must have two registered parents of the same breed, and meet the breed standard: a description of a certain "look" (physical conformation) and other features. This breed standard specifies what features are acceptable, which are preferred, and, sometimes, specifies particular features that, if present, disqualify the dog from being chosen as best of its kind. For example, an AKC-registered bulldog with the preferred face, ears, stance, size, and most other qualities of the breed, in an AKC-sanctioned confirmation show, would still be disqualified if it had a "brown or liver-colored nose" [1].

Each large kennel club hosts dog shows in which points are given for how well an individual dog compares to the breed standard, as compared to others of its type displayed at the same show. The male and female dogs competing in the top kennel clubs must be non-sterilized ("entire") animals and, although the gait and demeanor of the dog is evaluated as each walks around the show ring, the major emphasis is on body features. These contests are sometimes called conformational shows.

Increasingly, kennel clubs are catering to dogs and their owners through various shows and events other than conformational shows. The United Kennel Club was an innovator in this area; now such disciplines as agility, tracking, herding and carting are regularly sponsored by the American Kennel Club and others. Dogs may enter these shows and events whether or not they have been sterilized, and some of these events can include non-registered dogs and crossbreds as well.

Working dog organizations and registries

Other breeders concentrate on achieving uniform inherited behavioral traits in the dogs they produce. Some consider conformational traits important but secondary, some do not consider a dog's appearance at all, although this is rarer. Working, hunting, and herding dogs raised by field breeders sometimes only generally resemble the breed standard in appearance, but are more likely to be consistent in doing the job. The phrase "that dog don't hunt" comes from the rural United States and refers to a hunting dog that lacks the finer instincts of its breed <--!more specific, please, a reference to a group or territory where this is used, e.g.?-->

Independent breed clubs

These may include breeds-in-development, breeds recognized in only one country, and breeds where there are differences in type from the variety of the breed recognized by kennel clubs and their affiliates.

Natural breeds

In some parts of the world the isolation of dogs by geography (islands, mountain passes) has produced so-called natural breeds. These dogs are largely the product of natural selection. Members of a natural breed breed true - adults are similar to each other in appearance and behavior, and produce litters of puppies that not only grow up to resemble their parents, but - once grown, can between themselves propagate more litters of the breed. The Thai Bangkaew Dog is an example of a dog breed believed to have developed through isolation.

Sometimes these natural breeds have also undergone selective breeding by humans who desired a certain type of working dog. Such ancient working breeds include the Greyhound, the Mastiff and the Anatolian Shepherd Dog. Natural breeds made up many of the very first of the registered breeds, and also include some of the most recent additions to the list of breeds officially recognized by kennel clubs. Breed Recognition refers to the fact that a kennel club has officially acknowledged that the breed of dog has been shown to meet the requirements of the particular kennel club. This has nothing to do with the breed’s actual purebred status and the date of official recognition may have no relation to how long the breed has been known to be in existence. The Shar Pei is a natural breed, "having existed for centuries in the southern provinces of China, apparently to the Han dynasty, circa 200 BC". Despite the fact that statues of dogs that look just like the Shar Pei date back to the Thirteenth Century, the breed was not actually “recognized” until the later part of the Twentieth Century (initially by the Hong Kong Kennel Club). Other natural breeds have never been recognized formally by any kennel club.

Crossbreds

See the main article at mixed-breed dog.

There are modern dog breeders who purposely mate dogs of two completely different breeds in order to produce a litter of puppies with a set of desired characteristics that are not fully present in either individual parent. These crosses are sometimes called a “breed", but do not fulfill the requirement of "breeding true".

Although the hybrid puppies in the cross between two purebreds (in breeders' terms, the F1 generation) often all look alike, these puppies cannot grow up and be mated to other dogs that were born of the same crossed parentage and reliably produce new puppies that are like them. Crosses between purebreds have been used (along with mixed-breed crosses) to establish most of the long recognized dog breeds, but animal welfare advocates have openly deplored this method for any current propagation of a new breed. That's because it necessarily produces generations of mixed-breed puppies in a world where there is already a great overpopulation of such dogs. The breeders of Cocker Spaniel-Poodle crosses, “Cockapoos” and Labrador Retriever – Poodle crosses “Labradoodles”, however, counter that development of a new breed is a worthy goal, and that, with ethical breeding practices, all puppies can be properly placed. Some large commercial breeding operations that supply hybrid dogs have a different rationale: they claim to sell their puppies to pet shops under an agreement that every puppy is to be sterilized and therefore cannot ever used for breeding.

Mixed breeds (mongrels)

Though of uncertain parentage, mongrels are nonetheless respected

Dogs that came from parents who were not of any pure breed, or whose bloodlines comprise more than one breed, are called mixed breed. There are many other names for them, with varying levels of acceptability. The word ‘’mongrel’’, generally taken to be the correct formal word in dog fancy, is considered insulting by some dog lovers. That's probably because, in the English language, this word has sub-meanings that imply a lesser worth. However, it is fair to say that all dogs are derived from mongrels, and many scientists believe that in the absence of selective breeding, the dog would revert to the little brown pariah dog believed to be its most recent ancestor. Even the staunch proponents of purebreds generally agree that as pets, mixed breed dogs offer their owners the same qualities of loyalty, intelligence and companionship that have come to be associated with dogs.

Behavior, temperament, and skills

Dogs with special training can aid school children in learning social skills and provide stimulation for elderly patients in nursing homes.

Intelligence

See main article at The intelligence of dogs

Both anecdotal evidence and scientific research suggest that dogs have a reasonably high intelligence. This intelligence is expressed differently in different breeds and individuals, along with sets of specific behaviors and talents that appear to be inherited. Optimal socialization and training of an individual dog is partly dependant on its own intelligence, inherited behaviors, and temperament.

Natural behaviour

The qualities characterized under the categories Behaviour and temperament can have overlapping elements. These are related to intelligence, instinct and individual ability. They are often shaped by a dog’s individual personality and can be modified by training.

’’See main article at Dog behaviour

• instinctive herding
• instinctly chasing prey animals
• innate cleanliness, such as not fouling the “nest”. This is often found in natural breeds.

Temperament

• dog-on-dog aggression – A few breeds cannot help having this inborn trait and their breed standards allow it. The Rottweiler is an example. This is a natural behaviour and should not be confused with dog-on-human aggression.
• inherent gentleness - This is characteristic of breeds such as the Labrador Retriever
• dog-on-human aggression – this is almost universally condemned. In show dogs, aggression against humans results in immediately dismissal from the showring. (The dog is said to be “excused”.) Note that this undersireable trait should not be confused with the assertiveness acquired in the training of military and police dogs.
• observable loyalty – Loyalty is universally associated with dogs, but breeds such as the Miniature Fox Terrier are so particularly noted for it that this trait is written into the breed standard.

Special skills and ability

• speed – as exhibited by Greyhounds and Whippets, for example
• endurance - the Australian Kelpie’s breed standard requires that the dog gives the impression of having great stamina
• swimming
• jumping
• exceptional sight, smell or hearing

Training

Formal training in obedience and other disciplines is offered by many kennel clubs and private training organizations.

Since socialization to people and other dogs is part of the general training of puppies, many of the specialized training programs designed for dogs are given in classes. Not only do the dogs learn the skills taught, but they also learn to interact properly in a group situation.

Diet

If given the opportunity, dogs are omnivores, eating plant materials and animals. Generally, dogs will both scavenge carcasses and kill and eat animal prey.

Most standard dog care guides stress that dogs should not be fed table scraps, but only be fed a high quality commercial dog food.

Just as there are schools of thought about human diet, with advocates of various strict regimens ranging from macrobiotics to raw foods, there are a number of diets recommended for dogs that involve an entire philosophy of dog health. There are breeders who insist that puppies purchased from them be maintained on particular diets, and generally their wishes should be respected.

When purchasing a puppy from a breeder, or adopting from a shelter, it is wise to find out the diet that the animal has been maintained on, and to make only gradual changes.

In the developed world, excessive fat is a problem for many dogs. Obese dogs can have health problems, and can benefit from restriction of calories in the diet and from increased exercise. Puppies, especially large and giant breed puppies, can suffer joint problems if fed too much highly nutritious food early on. <--!I can’t figure out what the original author was trying to say with this sentence:That's because puppies can reach, or at least approach, their adult weight by 6 months to 12 months of age, and if that adult weight and size is large, the bones may not have a chance to strengthen suitably to offer healthy support.-->

Dog health

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. Dogs, like all mammals, are also susceptible to heat exhaustion when dealing with high levels of humidity and/or extreme temperatures.

Diseases

Most diseases are species-specific; so generally the diseases that affect dogs cannot be transmitted to humans, and vice versa. Rabies is an exception to this rule (see below). (Compare this with parasites, many of which can be transmitted between species.) 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 (except the many infections which are species specific) like hypothyroidism, cancer, dental disease, heart disease, etc.

Vaccinations

Immunizations are available for many of the infectious diseases that affect dogs. Some of these diseases are passed from dog to dog, others to dogs through insects. Vaccinations for canine distemper, hepatitis, leptospirosis, parainfluenza, canine parvovirus, Lyme disease and rabies are available. Some of these are combined in "one shot", and one - rabies - is often legally required of dog owners to provide for their dogs. That's because rabies is a fatal disease that can be transmitted by the bite of an infected dog.

Some of these illnesses are only prevalent in certain regions of the world, and the selection of which immunizations is important varies according to geography.

Parasites: treatment and prevention

Unlike diseases, some parasites can be passed between dogs and humans. Common external parasites are various species of fleas, ticks, and mites. Internal parasites include hookworms, tapeworms, roundworms, and heartworms.

Generally, prevention of these parasites involves the administration of a systemic medicine or the use of applied chemicals through the wearing of collars or other means.

Common breed-related disorders

Some breeds of dogs are especially prone to certain genetic ailments, such as hip dysplasia, luxating patellas, cleft palate, blindness, or deafness. Dogs are also susceptible to the same ailments that humans are, including diabetes, epilepsy, cancer, and arthritis. Gastric torsion and bloat is a dangerous problem in some large-chested breeds.

Almost every breed of dog has an organized group of fanciers promoting it. Doing an internet search on the breed will yield a number of breeder sites, along with the various fanciers' organizations' web sites. Usually, one or more of the sites will list not only the attributes that are wonderful features of the breed, but any special health problems along with information for diagnosis and treatment.

Lifespan

The typical lifespan of dogs varies considerably by breed, and seems to be somewhat related to size. 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.

Other dog-human issues

Overpopulation

According to the Humane Society of the United States, 3-4 million dogs and cats are euthanized each year in the United States and many more are confined to cages in shelters because there are many more animals than there are homes. Spaying or neutering dogs helps keep overpopulation down.[2] Local humane societies, SPCA's and other animal protection organizations urge people to spay or neuter their pets and to adopt animals from shelters instead of purchasing them.

Dog/Wolf hybrids

In the wild, in areas where wolves still roam but the human population is also established, there is the occasional inter-breeding of wolf and dog. Since a wolf pack is not likely to perceive a dog as anything but prey, and a domestic dog is unlikely to survive attack from even a lone wolf, this is not as common as the interbreeding of dogs and coyotes in similar circumstances. When dogs and coyotes do interbreed in the wild, the resulting hybrids often fail to thrive because they lack behavior features of the wild canine parent. For example, the domestic bitch ordinarily comes into heat twice or more times a year, where as the coyote female is fertile only once a year. The timing of the dog's estrus does not correspond to the local seasons in a way that is advantageous to a newborn litter, and so puppies born in the lean times of winter or drought are more likely to die. The instinct to only allow one mating pair of animals in the pack and the nurturing instincts of other pack members ( including the males) towards that pair's pups, is almost completely lost in the dog; and so hybids in the wild are less able to raise litters that survive.

A dog/wolf hybrid.

In human society, there are people who selectively breed wolves and dogs as pets. In many areas, there are currently laws against keeping wolves in captivity, but there are regions where this is not the case. Often, the breeder of these hybrids works not from full wolves, but selects a hybrid wolf/dog as one parent, and either another hybrid or a domestic dog as the other parent.

Molecular genetic research has shown that dogs appear to have been domesticated from wolves, but not from wolves in general - instead, selected individual ancient wolves were kept and interbred. There is speculation that among the wolves that harried these early human settlements or frequented ancient dumps, the particular individuals chosen for "adoption" by people were probably not only very young - but were exceptionally "nice". There is variation in behavioral characteristics of individual members in every large group of wolves. It is not likely that the wild wolf pup who is at the extreme for aggressiveness, for example, would be tolerated in human society - once grown into an adult wolf, even if originally adopted in its infancy.

That has been the overall situation with wolf/dog hybrids. Even if carefully raised from birth, some adult wolf/dogs do not remain "tame" enough to safely interact with people. Breeders of wolf/dog hybrids routinely remove the puppies from the mother by 2-3 weeks of age, and hand raise them, bottle feeding the puppies every few hours. Each puppy is allowed contact with at least one other puppy, but all puppies are kept isolated from adult dogs and wolves (including their own mother) because if they are allowed contact they usually will not bond to their human handlers. That, of course, is not the case in pure domestic dog puppies, who can ordinarily be raised in the home with free access to both mother and human companions. Even with special nurturing of wolf/dog pups, and even though these hybrid puppies are usually much less than 50% wolf, there is an extremely high rate of attacks on humans by adult hybrid wolf/dogs - including the members of the human family that raised them. Breeders of hybrid wolf/dogs counsel that these dogs must at all times be fenced off from any possible contact with strangers [3]. Fatal human attacks by hybrids are not rare, and often victimize children.

Notable dogs

See the main article at: famous dogs.

Many dogs have earned a high level of fame, some to the point where the name of the animal has become recorded in history.

None of the following dogs are fictional, and each of them helps illustrate the range of accomplishments of working and companion dogs.

• Barry: A Newfoundland dog who saved the lives of forty people who had been lost in snowstorms in the Swiss Alps.

• Balto: (1922 – March 14, 1933) was a lead sled dog in the 1925 serum run to Nome, in which diphtheria antitoxin was transported from Anchorage, Alaska to Nome by dog-sled teams to combat an outbreak of the disease.

• Brandy: the first "seeing-eye dog" in the United States.

• Greyfriars Bobby: This Syke Terrier from the nineteenth century became famous for waiting every day (barring bad weather) by his master's grave for his return in Edinburgh, Scotland for fourteen years.

• Hachikō: A faithful Akita.

• Rin Tin Tin: unlike Lassie, the original Rin Tin Tin was a real dog. His success was credited with saving Warner Brothers film studio from bankruptcy.

References

Further reading

• Brewer, Douglas J. (2002) Dogs in Antiquity: Anubis to Cerberus: The Origins of the Domestic Dog, Aris & Phillips ISBN 0-85668-704-9
• Coppinger, Raymond and Lorna Coppinger (2002). Dogs: A New Understanding of Canine Origin, Behavior and Evolution, University of Chicago Press ISBN 0-226-11563-1
• Cunliffe, Juliette (2004). The Encyclopedia of Dog Breeds. Parragon Publishing. ISBN 0-7525-8276-3.
• Derr, Mark (2004). Dog's Best Friend: Annals of the Dog-Human Relationship. University of Chicago Press. ISBN 0-226-14280-9
• Donaldson, Jean (1997). The Culture Clash. James & Kenneth Publishers. ISBN 1-888047-05-4 (paperback).
• Fogle, Bruce, DVM (2000). The New Encyclopedia of the Dog. Doring Kindersley (DK). ISBN 0-7894-6130-7.
• Grenier, Roger (2000). The Difficulty of Being a Dog. University of Chicago Press. ISBN 0-226-30828-6
• 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 0-688-12841-6 (trade paperback).
• Pfaffenberger, Clare (1971). New Knowledge of Dog Behavior. Wiley, ISBN 0-87605-704-0 (hardcover); Dogwise Publications, 2001, 208 pages, ISBN 1-929242-04-2 (paperback).
• Savolainen, P. et al. (2002). Genetic Evidence for an East Asian Origin of Domestic Dogs. Science 298. 5598: 1610–1613.
• Shook, Larry (1995). "Breeders Can Hazardous to Health", The Puppy Report: How to Select a Healthy, Happy Dog, Chapter Two, pp. 13–34. Ballantine, 130 pages, ISBN 0-345-38439-3 (mass market paperback); Globe Pequot, 1992, ISBN 1-55821-140-3 (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. 57–72. Ballantine, 130 pages, ISBN 0-345-38439-3 (mass market paperback); Globe Pequot, 1992, ISBN 1-55821-140-3 (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 0-395-66958-8.
• Verginelli, F. et al. (2005). Mitochondrial DNA from Prehistoric Canids Highlights Relationships Between Dogs and South-East European Wolves. Mol. Biol. Evol. 22: 2541–2551.
• Vilà, C. et al. (1997). Multiple and ancient origins of the domestic dog. Science 276:1687–1689. (Also "Multiple and Ancient Origins of the Domestic Dog")

External links

• American Kennel Club
• Australian National Kennel Club
• Canadian Kennel Club
• Fédération Cynologique Internationale (FCI) - World Canine Organisation
• FCI International breed standards
• The Kennel Club (UK)
• New Zealand Kennel Club