Dogs are also viewed as being the single most genetically diverse species on Earth - largely thanks to human-imposed selective breeding, the vast array of dog breeds surpasses any other creature on the planet. Due to selective breeding by man, however, many breeds of dog have significant [[gene|genetic]] disorders. These include hip dysplasia (common with German Shepherds), and respiratory problems caused by shortening of the face, as seen with Boxer dogs and the Bulldog's lip. To overcome the prevalence of genetic disorders rendered common by inbreeding, many breeders regularly practice outcrossing, or introducing new material into a breed line via mating with other kinds of dog. This restores vigor to a breed and can decrease the likelihood of genetic disorders manifesting. | Dogs are also viewed as being the single most genetically diverse species on Earth - largely thanks to human-imposed selective breeding, the vast array of dog breeds surpasses any other creature on the planet. Due to selective breeding by man, however, many breeds of dog have significant [[gene|genetic]] disorders. These include hip dysplasia (common with German Shepherds), and respiratory problems caused by shortening of the face, as seen with Boxer dogs and the Bulldog's lip. To overcome the prevalence of genetic disorders rendered common by inbreeding, many breeders regularly practice outcrossing, or introducing new material into a breed line via mating with other kinds of dog. This restores vigor to a breed and can decrease the likelihood of genetic disorders manifesting. |