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The point at which a new variety becomes a breed can be difficult to decide. National kennel clubs often differ in their recognition of breeds and rare breeds might not be recognised outside their home country. Usually, only dogs recognized by a kennel club are eligible to compete in that specific club's conformation shows and dog sports, although many dog sports allow any healthy dog to compete regardless of the breed.
Generally, before a type of dog is recognized as a breed, it must be shown that mating a pair of that type always produces dogs that have the same characteristics as the parents, usually both in appearance and in behavior. This is known as breeding true. There are many issues concerning what is considered breeding true. For example, Flat-Coated Retrievers must always be black; however, yellow coats occur occasionally in some litters. Kennel clubs do not recognize the yellow dogs as legitimate members of the breed; some breeders will kill the puppies rather than risk having the dog grow up, breed, and produce more of the undesired yellow color, perpetuating the undesireable gene; more often, today, such dogs are neutered and placed in homes as pets. As another example, a breeding pair of Belgian Shepherds of the Groenendael variety can produce puppies of the Tervueren (brown) variety; the AKC considers the varieties to be different breeds and, therefore, the brown puppies are invalid and undesirable dogs, whereas the CKC considers them simply to be different color varieties of the same breed.
A Jack Russell Terrier playing with his toy.
The dog has developed into hundreds of breeds with a great degree of variation, such as this Miniature Pinscher and Boxer.
A Maltese enjoying the fall leaves.
There are numerous dog breeds, with over 800 being recognized by various kennel clubs 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.
A few basic 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.
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 dog shows. Even prize-winning purebred dogs sometimes possess crippling genetic defects due to founder effect or inbreeding.
These problems are not limited to purebred dogs and can affect mixed-breed populations. 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.
A 10-year-old Staffordshire Bull Terrier/Labrador cross enjoys the sunlight.
In February 2004, the Canine Studies Institute in Aurora, Ohio, arranged recognized breeds of dogs into ten categories. |
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