View source for Dog

{{Taxobox
| color = pink
| name = Domestic dog
| status = 
| image = 
| image_width = 
| image_caption = 
| domain = [[Eukaryota]]
| regnum = [[Animal]]ia
| phylum = [[Chordate|Chordata]]
| subphylum = [[Vertebrate|Vertebrata]]
| classis = [[Mammal]]ia
| ordo = [[Carnivora]]
| familia = [[Canidae]]
| genus = ''[[Canis]]''
| species = ''[[Grey Wolf|C. lupus]]''
| subspecies = '''''C. l. familiaris'''''
| trinomial = ''Canis lupus familiaris''}}

Most recent approved version of [[Dog]]

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

Dogs and people may communicate better than any other two [[species]].<ref>Stephen Budiansky, The Truth about Dogs: An Inquiry into Ancestry Social Conventions. Mental Habits Moral Fiber ''Canis familiaris''. 2001 ISBN 014100228X</ref> , 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|Training section]]).
 
==The domestic life of dogs==
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 animal]]s. Although the instincts to behave in ways that ease interactions in the [[pack (canine)|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]]". 
[[Image:Sleeping Pups.jpg|thumb|left|250px|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 [[Socialization|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 who 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. 

Female dogs (called'' bitches'') ordinarily give birth to more than one puppy at a time (sometimes to more than a dozen!). The group of puppies born together is called a ''litter''. In other words, being born in a litter is the natural lot of the dog, and that means 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.
[[Image:Cachorro.jpg|thumb|right|250px|The archetypical "friendly dog" apperance]]

Dogs fill a variety of roles in [[human society]] and are often trained as [[working dog]]s. 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. The most common (and perhaps most important) role of dogs in many countries is as a human [[companion dog|companion]].

==Dog breeds==
[[Image:Shar pei welpen.jpg|thumb|left|250px|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 ''[[Dog breed|breed]]s '' 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 [[selective breeding|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 [[purebreed]]s 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 disasterous consequences for the health of the female dog. Dogs also have an incredibly broad range of ''coat'' (fur) and skin [[Dog colors|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 [[List of dog breeds|800]] [[dog breed]]s are recognized by [[breed club|breed]] and [[kennel club]]s 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" [http://www.akc.org/breeds/bulldog/index.cfm?SEARCH_BUTTON.X=15\&SEARCH_BUTTON.Y=10].   

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 un-neutered ("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. 

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]]s, 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 registered by kennel clubs.  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".<ref>Source for quote: ''Chinese Shar-Pei'' in The Complete Dog Book, Official Publication of the American Kennel Club, 20th Edition, Ballantine Books, New York, 2006,page 543</ref> 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 registered 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.

===Crosses===

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 present in either parent. These crosses are sometimes ''called'' "a breed", but do ''not'' fulfill the requirement of "breeding true". For example, a pure bred [[Poodle]] and pure bred [[Cocker Spaniel]], if crossed, usually will produce a litter of puppies that all look very much alike. This particular cross has the name [[Cockapoo]]. The poodle is one parent of another popular cross, the [[Labradoodle]], in which the other parent is a [[Labrador Retriever]]. Why choose the poodle for cross breeding? The poodle's unique coat does not shed. This quality reduces both housecleaning requirements and dog allergy symptoms in owners, and is one of the reasons prompting both crosses (see [[Choosing a dog]] - Allergy).

Although the hybrid puppies in the cross between two purebreds (sometimes called 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. If a breeder ''does'' mate a mother from one of these crosses (let's say Cockapoo) to a father dog who is also a first generation Cockapoo, a few of their puppies ''may'' have the desired set of qualities - but sometimes none will, and often those few that do are in the minority of a large litter. This leaves several puppies who are [[Mixedbreed dog| mixed breed]] dogs (see below), and at high risk for joining their brethren in the shelters and streets of the world as unwanted pets. However, if the breeder continues to work with such a cross over many generations - being careful not to often mate individuals who are immediately related to each other ([[inbreeding]]) in order to avoid bringing out harmful recessive traits that cause disease, eventually healthy dogs may be produced who do, in fact, breed true. Once such crosses can be bred so that all members of a litter reliably resemble the breed standard, then a new purebred breed has become established, and fanciers usually campaign to have it recognized by a kennel club.

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 Cockapoos and 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. Large commercial breeding operation that supply hybrid dogs have a different rationale. They sell their puppies to pet shops under an agreement that every puppy is to be sterilized and not ever used for breeding.

===Mixed breeds (mongrels)===
[[Image:PICT1094.JPG|thumb|right|250px|Though of uncertain parentage, mongrels are nonetheless respected]] 

Dogs who came from parents who were not of any breed, or more than one breed, are called [[Mixedbreed dog|mixed breed]]. There are many other names for them, and some are not very polite. Even the word, mongrel, which is one of the most common names given them, 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 that, far from having a lesser worth, mixed breed dogs may well offer their owners "the best of everything" having to do with dogs.

==Behavior, temperament, and skills==
{{main|Dog intelligence}}
[[Image:Schulhund-ina-in-schulklasse.jpg|thumb|right|250px|Dogs with special training can aid school children in learning social skills and provide stimulation for elderly patients in nursing homes.]]

Both [[anecdotal evidence]] and [[Scientific method|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.

For example, [[Border Collie]]s are noted for their ability to learn complex commands on dry land, while [[Newfoundland Dogs]] are known as powerful swimmers who can be trained to rescue the drowning. There are many breeds of retrievers, all of them share the propensity to not only chase that ball (or rabbit) but to bring it back. In the days when retrievers were all hunting dogs, only those animals that were excellent fetchers were bred, the puppy who might be beautiful and affectionate, but who remained totally uninterested in delivering the goods, was not propagated. One criticism lodged at breed registries such as the American Kennel Club is that success in the show-ring is based on conformation rather than on working ability. The AKC does sponsor field trials, however, for working and hunting dogs. If a retrieving retriever is what's wanted, the person shopping for a puppy might be advised to look for field championships in the puppy's pedigree, and not just awards for body type. On the other hand, though more likely to have the skill, a puppy born of even the great retrievers may not itself be inclined to retrieve.

Many of the working dog breeds, such as Rottweilers, Dobermans, German Shepherd Dogs, and Anatolian Shepherds, are characterised by kennel club breed standards as having a temperment such that a good specimen of the breed is "reserved with strangers". Unlike a typical Labrador retriever, these dogs require extensive introduction to general human society as puppies, during the sensitive period. Although any breed of dog may bite if provoked, the working dog breeds have been most often named in unprovoked lethal attacks on humans. In these tragic cases, poor socialization of the dogs- or even purposeful training by their owners to encourage the dogs to fight other dogs and attack any stranger, has been cited as the problem by dog fanciers. Breeders of working dogs often recommend that such breeds, as puppies, are brought daily to shopping areas, and streets with pedestrian traffic, where- closely supervised by their owners, they are allowed to be approached by a variety of selected strangers who agree to give them a treat. There is a concern that such dogs, if limited to the back yard or house and to only the immediate family as they are raised, can grow up to be inappropriately aggressive towards people met for the first time, out of a fear reaction. Extensive early socialization with strangers will not remove the usefullness of such dogs for protection of the home, but is advocated to make them safe canine citizens in human society. Formal training as therapy dogs is also suggested by some working dog breeders, as another means of ensuring proper behavior. 

Some of the individual dogs who most easily learn complex tasks are among the most difficult dogs to integrate into a normal household. [[Border collies]] are an excellent example of a breed that is both known for its intelligence and for its over-representation in animal shelters, as are [[Jack Russell terriers]]. When typical of their breed, these dogs are not suitable for a household where no one is home for hours at a time and no barn patrol or other work is available for the dog. Like all dogs who are both "high energy" ''and'' high in canine intelligence, these two breeds are examples of dogs that usually require a great deal of attention and do best when kept busily engaged. When left alone for hours at a time, they are very unlikely to curl up and go to sleep. Especially when young, smart, high energy dogs are more likely to dismantle the furniture if left inside the house or apartment, or to test a neighbor's prize thoroughbred mare's capability of jumping out of its fenced pasture, if left to wander free out in the country. There are better choices for an absent owner. This is even true of the venerable [[Labrador retriever]], which, thanks to its outgoing, gentle, and eager-to-please nature, has been the most popular registered breed in the United States since 1991[http://www.akc.org/pdfs/press_center/popular_pooches.pdf] It is also the most common breed found abandoned to dog shelters because of behavioral problems that develop when owners fail to provide these highly intelligent and energetic dogs the exercise and attention they need.

===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.

==Health, care, and breeding of dogs== 	 
Modern [[dog breed]]s show more variation in size, appearance, and behavior than any other domestic animal. When [[Choosing a dog|choosing a dog]], these factors are all best taken into consideration along with the particular animal's age, circumstances, and background. 

Within the range of extremes, dogs generally share attributes with their wild ancestors, the [[Gray Wolf|wolves]]. Dogs are both [[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 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 bred to particularly utilize vision in tracking prey. These beeds include the [[greyhound]] and [[Afghan hound]].<ref>{{cite web | last = | first = | authorlink = | coauthors = Jonica Newby, Caroline Penry-Davey | title = Catalyst: Dogs' Eyes | work = | publisher = Australian Broadcasting Corporation | date = 2003-09-25 | url = http://www.abc.net.au/catalyst/stories/s953902.htm | format = | doi = | accessdate = 1st April 2007 }}</ref> The most extreme [[sighthound]]s 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 [[Hertz|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, 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.<ref>[http://www.lsu.edu/deafness/HearingRange.html How well do dogs hear?] Accessed 1st April 2007</ref>

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 sensory experience in olfaction, as compared to ours. Some breeds have been selectively bred for excellence in detecting scents, over and above their canine brethren, such as the scent hounds including [[Blood hounds]].

==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 pets|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. 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.<ref>{{cite web|url=http://www2.dasnr.okstate.edu/index.php?option=com_content&task=view&id=257&Itemid=103 |title=Summer heat can be tough on pets |accessdate=2006-08-21 | first = Trisha | last = Gedon | date = 2006-05-25 | work = Division of Agricultural Sciences and Natural Resources | publisher = Oklahoma State University }}</ref>

===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 (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. [[vaccination|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===	 
Common external [[parasite]]s are various species of [[flea]]s, [[tick]]s, and [[mites]]. Internal parasites include [[hookworm]]s, [[tapeworm]]s, [[roundworm]]s, 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 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.

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.

===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.[http://www.spayusa.org/main_directory/02-facts_and_education/stats_surveys/javma_articles/02dogs-cats-sterilized.asp] 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 [[coyote]]s 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.
[[Image:Wolf_dog.jpg|thumb|right|250px| 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 [http://www.wolfpark.org/wolfdogs/guidelines.html]. Fatal human attacks by hybrids are not rare, and often victimize children.

==Notable dogs==
Many dogs have earned a level of fame, 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''': Buried in an island graveyard in the River Seine in Paris, lies this Newfoundland dog who patrolled the St. Bernard Pass in the Swiss Alps.  The monument depicts him saving a child, and in fact he saved the lives of forty people who had been lost in snowstorms in those mountains.<ref>A Hero Dog The Watchman (1894-1906). Boston: Nov 8, 1900. Vol. 81, Iss. 45; p. 22 (1 page)</ref> 

'''[[Balto]]''' (1922 &ndash; 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.  Balto and his team became famous during coverage of the event, and went on to tour the country before being placed in a Cleveland Zoo.

'''Brandy''':  was the first "seeing-eye dog" in the United States. Although guide dogs for the blind had become accepted in Germany in the early twentieth century, American organizations for the blind scorned their use."<ref> Source for quote: Brandy Chapter in Dog Heroes, Tim Jones, Epicenter Press, Seattle, 1995 page 37)</ref> The head of one prestigious school for the blind described the guide dog as 'a dirty little cur dragging a blind man along at the end of a string, the very index of incompetence and beggary."  A young American blind man, Morris Frank, fought for a full and independent life at a time when this was not considered possible for a person like him. He traveled to Switzerland, at the invitation of the trainers Dorothy Eustis, and there went through an extensive course of training with a German Shepherd bitch he named "Brandy". He returned to New York City and, in the glare of flashbulbs, showed reporters that he, a blind man, could walk (with Brandy) across some of the busiest and most dangerous streets in the city. His subsequent travels across the country demonstrated that a blind person could be guided by a dog and achieve independence.

'''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.

==References ==
===Citations===
<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&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 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&ndash;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&ndash;2551.
* 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"])

==External links==

*[http://www.akc.org/ American Kennel Club]
*[http://www.ankc.aust.com/breed_list.html Australian National Kennel Club]
*[http://www.ckc.ca/ Canadian Kennel Club]
*[http://www.fci.be Fédération Cynologique Internationale (FCI) - World Canine Organisation]
*[http://www.dogdomain.com/fci-1.htm FCI International breed standards]
*[http://www.the-kennel-club.org.uk The Kennel Club (UK)]
*[http://www.nzkc.org.nz/dogselect.html New Zealand Kennel Club]

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