Genetic diseases often affect purebred dogs more than mixed breeds, but recent research challenges the assumption that mutts are naturally healthier.
The Study on Purebreds vs. Mixed Breeds
The belief that mixed breeds are healthier than purebreds is common, yet a 15-year study from the University of California, Davis, suggests otherwise. Researchers analyzed records from over 90,000 dogs treated at the university’s veterinary medical teaching hospital between 1995 and 2010. The team found over 27,000 records involving at least one of 24 genetic disorders, including various cancers, heart disease, and epilepsy.
Surprisingly, the study showed that the prevalence of 13 of the 24 disorders was about the same for purebreds as for mixed breeds. These conditions included hip dysplasia, hyper- and hypoadrenocorticism, and patellar luxation.
However, ten conditions were found more frequently among purebred dogs, such as dilated cardiomyopathy, elbow dysplasia, and hypothyroidism. The only disorder found more often in mixed breeds was cranial cruciate ligament (CCL) disease.
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“Overall, the study showed that the prevalence of these genetic disorders among purebred and mixed-breed dogs depends on the specific condition,” said Anita Oberbauer, Ph.D., a professor and chair of the Department of Animal Science at UC Davis and lead author of the study.
Breed-Specific Risks
The data also indicates that breeds sharing a similar lineage are more prone to certain inherited disorders. For example, four of the top five breeds affected by elbow dysplasia were the Bernese mountain dog, Newfoundland, mastiff, and Rottweiler—all from the mastiff-like lineage. This suggests these breeds share gene mutations for elbow dysplasia because they descended from a common ancestor.
On the flip side, disorders that occur in both mixed breeds and purebreds often trace back to well-established gene mutations that have spread throughout the dog population. These include hip dysplasia, tumor-causing cancers, and hypertrophic cardiomyopathy.
While the study confirms that purebreds are not universally sicker, the focus on physical characteristics in breeding practices remains a significant concern. Many breeders prioritize specific traits, sometimes at the expense of health and longevity, which can lead to lifelong suffering for the animals.
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Managing Health Through Nutrition
Just because a dog has a genetic predisposition to a condition does not mean it will develop the disease. Nutrigenomics is an emerging field that studies the effect of nutrition on the genome. It suggests that nutrition can influence gene expression, potentially helping to suppress or encourage certain genetic traits.
Every individual has a unique molecular dietary signature that determines which nutrients are essential for thriving. As veterinarians and pet parents, there is some control over how these nutrients affect a dog’s health. For instance, if a dog is genetically predisposed to a certain health problem, specific nutrients might be used to manage the condition or slow its progression.
For more information, pet owners can review resources like the Canine Inherited Disorders Database or the Inherited Diseases in Dogs database provided by the University of Cambridge Veterinary School. DNA test kits are also available to identify breed ancestry and potential genetic traits, which can be reviewed with a veterinarian to create a preventative care plan.
