Not so with dogs, whose genome produces more than 300 breeds as distinct from each other as Great Danes and Chihuahuas. This means that the genes controlling these traits are few, because you can't select a huge number of genes in a small number of generations. In addition to narrowing the genetic field for the study of basic biological questions, dogs, with their widely varying yet ingrained behavior, offer a unique opportunity to study complex social behaviors. Nervousness, aggression, or shyness is also common in a breed-specific manner. These traits, which are difficult to pinpoint in people, are easily explored in dogs.
Dogs are biomedically a key species because they are subject to many of the same diseases as humans.
Too, dogs are biomedically a key species because they are subject to many of the same diseases as humans. Some of these diseases are found only in dogs and humans, such as X-linked retinal degeneration. Often, as with functional heart abnormalities such as arrhythmia, the dog disease represents a naturally occurring model of one that is rare and hard to study in humans. At present, more than 300 inherited diseases of dogs are being catalogued. When it comes to the development of gene therapies, dogs are an important intermediate species between the human and the mouse.