Study reveals genetic diseases of mixed-breed, purebred dogs

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A study has identified genetic diseases that mixed-breed dogs are likely to develop, also finding that fewer mixed-breed dogs than purebred dogs are affected by the disease-causing mutations tested.

Wisdom Health and Genoscoper Laboratories, which offer genetic tests for dogs and cats, published "Frequency and distribution of 152 genetic disease variants in over 100,000 mixed breed and purebred dogs" on April 30 in PLOS Genetics, an online journal of the Public Library of Science.

The study examined the DNA of 83,000 mixed-breed dogs and of 18,000 purebred dogs representing 330 breeds, types, and varieties. Disease mutations tested included those for progressive retinal atrophy, hyperuricosuria, Collie eye anomaly, multidrug sensitivity, and von Willebrand's disease.

Largest Ever Dog DNA Study

"There has been a long-standing perception that mixed breed dogs are less disease-prone than purebred dogs," said Dr. Cindy Cole, general manager at Wisdom Health, in an announcement about the study. "This DNA-testing–based evidence shows that while mixed breed dogs are in fact less likely than purebreds to develop the recessive disorders evaluated in the study, they may still be carriers."

On the basis of 152 diseases tested, approximately two out of 100 mixed-breed dogs were at risk of becoming affected, and 40 out of 100 were carriers for at least one of the diseases. Approximately five out of 100 purebred dogs were at risk of becoming affected, and 28 out of 100 were carriers for at least one of the diseases.

The research also indicated that through healthy breeding practices, which often include genetic testing, some diseases appear to have been eradicated from breed pools. For example, X-linked severe combined immunodeficiency, a mutation originally found in Basset Hounds, appears to have been eradicated.

The ocular, nervous, and circulatory systems were the most commonly affected across both the purebred and mixed-breed dog populations in the study.

Related JAVMA content:

Unlocking the genetic secrets of your dog (March 15, 2017)

Disease-associated gene variants widespread across dog breeds (March 15, 2017)

AVMA passes policy on responsible pet breeding (March 1, 2017)