Dogs (Canis familiaris) exhibit greater phenotypic diversity than any other mammalian species, spanning differences in size, coat, head shape, and behavior. This diversity did not arise from natural selection but from domestication and human-guided breeding. More than 400 distinct breeds have been recognized, each developed to fulfill roles such as hunting, herding, guarding, or companionship.
According to Giger, Sargan, and McNiel (2006), selective breeding has also increased the prevalence of hereditary diseases. Restrictive gene pools, popularity-driven breeding, and conformation standards have allowed deleterious variants to persist within certain breeds. While dogs were historically bred for tasks and companionship rather than economic utility, these practices inadvertently heightened genetic risks.
The study highlights that even within breeds, suitability for work or companionship can vary significantly due to heterogeneous genetic backgrounds. This reinforces the need for genetic screening to reduce inherited disorders and improve welfare. Such efforts are especially vital in breeds prone to conditions like hip dysplasia, cardiac diseases, or inherited metabolic disorders.
Ultimately, the authors argue that responsible breeding and modern genomic tools can help balance the preservation of canine diversity with the mitigation of hereditary health risks. This work underscores the responsibility of breeders, veterinarians, and dog owners in ensuring the health and longevity of future generations of dogs.
Source: Giger, U., Sargan, D., & McNiel, E. (2006). Breed-specific Hereditary Diseases and Genetic Screening. Cold Spring Harbor Monograph Archive, 44, 249–289.
