Genetic Diseases in Dog Breeds, and Why DNA Testing Helps

Key Takeaways

• Some purebred dog breeds are prone to specific inherited genetic diseases due to breeding within a limited gene pool.
• Well-known examples include MDR1 (drug sensitivity in herding breeds), von Willebrand disease (vWD) bleeding disorder, and DCM heart disease.
• DNA testing helps screen before breeding and plan preventive health care.
• But carrying a risk gene doesn't guarantee disease — especially for recessive conditions. Always consult a veterinarian.

Why do some dog breeds have "signature diseases"? The answer lies in genetics and breeding history. As a veterinarian, I want to explain the inherited diseases seen in dogs and why DNA testing is such a powerful care tool.

Why Do Purebred Dogs Have Breed-Specific Diseases?

Selective breeding for desired traits (build, coat, temperament) is often done within a limited population, which lets disease-causing recessive genes be passed on and accumulate within a breed. A study analyzing nearly 90,000 dogs found at least 10 disorders more common in purebreds than mixed breeds, such as aortic stenosis, early-onset cataracts, dilated cardiomyopathy (DCM), and gastric dilatation-volvulus (GDV).

Examples of Important Inherited Diseases

• MDR1 (ABCB1 gene) — causes abnormal sensitivity to certain drugs, common in herding breeds like Rough Collies, Shetland Sheepdogs, and Australian Shepherds. A Thai study also found a high frequency of this gene in collies.
• Von Willebrand disease (vWD) — the most common inherited bleeding disorder in dogs, recessively inherited, found in several breeds such as the Doberman.
• Dilated cardiomyopathy (DCM) — common in large breeds, with a genetic component alongside other factors.
• Hereditary skin diseases — several are monogenic and breed-specific.

How Does DNA Testing Help?

A panel test can screen dozens of variants at once. The main benefits are:

• Responsible breeding plans — avoid pairing two carrier parents.
• Pre-medication alerts — e.g., knowing MDR1 status before giving a potentially dangerous drug or high dose.
• Preventive care — watch early for signs of diseases your dog is at risk for.

A Key Point: A Risk Gene Isn't a Verdict

What I really want to stress: finding a risk gene doesn't mean your dog will definitely get sick — especially for recessive conditions, which require two copies of the faulty gene to show symptoms. A "carrier" (one copy) usually doesn't fall ill, and carriers shouldn't all be removed from breeding without expert advice. Many of these disorders also occur in mixed-breed dogs, so results should always be interpreted with a veterinarian.

Author's Final Note

DNA testing isn't meant to create worry — it's about "knowing early, caring early." Understand your dog's individual risks, then plan their health so they can live the longest, happiest life possible.

References

1. Genetic Panel Screening of Nearly 100 Mutations Reveals New Insights into the Breed Distribution of Risk Variants for Canine Hereditary Disorders. PMC. NCBI
2. Ten Inherited Disorders in Purebred Dogs by Functional Breed Groupings. PMC (UC Davis). NCBI
3. Prevalence of the MDR1 Gene Mutation in Herding Dog Breeds and Thai Ridgebacks in Thailand. PMC. NCBI
4. Von Willebrand Disease. Cornell Riney Canine Health Center. Cornell
5. Von Willebrand Disease I (vWD Type 1). UC Davis Veterinary Genetics Laboratory. VGL
6. Inheritance of Monogenic Hereditary Skin Disease and Related Canine Breeds. PMC. NCBI