It is important to note that all existing dog breeds began as mixed breeds at one point, either by random occurrence or by deliberate crosses of existing breeds. Even before the existence of formal breed standards and breed clubs, breeders encouraged desirable traits and discouraged others by selectively breeding only their best bitches and dogs.
Mixed breeds can be very roughly divided into two types:
Mongrels are random-bred dogs or mixes among dogs of unknown origin, occuring without any planning or supervision of humans. As a result, there is no precise definition of temperament and traits and transmission of specific characteristics in their progeny is uncertain. The zoological term "mongrel" is sometimes used in a derogative way to denote an "inferior dog", especially in the US. The words mutt, cur and tyke also occur in this sense. Therefore, many owners prefer the word mixed-breed.
Hybrid dogs or crossbred dogs (or crossbreeds), which result from the crossing of two dogs of known ancestry, of which at least one is pure-bred. Strictly speaking, hybrid dogs refer to a a first-generation cross between two pure-bred dogs, while the term crossbreed may be used for any dog of which at least one parent or grandparent is a pure-bred. "Designer dogs" are exemples of hybrid dogs. Crossbreeds occur as foundation stock for breeding programs for the creation of new breeds or rescue programs for ancient breeds that are on the verge of extinction. Other crossbreeds occur when breeders are hoping to add or reinforce characteristics from one breed into another breed.
The main difference between the first and the second type is that, over several generations of mixed breeding, mongrels will tend to revert back to a natural, moderate canine type. This generic canis familiaris, seen in feral or pariah dog populations, where mixed breeding has occurred over many generations, tends to be light brown and of mid-size, with pricked ears and tails carried over their backs. This basic physical dog type might also represent the common ancestor of all modern dog breeds.
On the contrary, crossbreeds occur, per definition, by human intervention and, therefore, are usually intended to become fixed in type, sometimes leading to the recognition of a new breed. As hybrids dogs usually refer to first generation crosses they are not recognized by the main registries. Independent breeds or re-created breeds may also be the product of crosses, but the main distintinction lies in the number of specimens and the number of generations that breeds true to type, as well as the numbers of breeders and the existence of a breed registry and breed standard. To stand a chance to be formally recognized as a breed, the dogs must also have predictable characteristics, fulfill a specific purpose, and have a national parent breed club.
The American Mixed Breed Obedience Registration was established in 1983 in an effort to improve opportunities for mixed-breed dogs and to acknowledge the efforts and achievements of their handlers in obedience and agility competition.
