Dr. Cathryn Mellersh, BVSc, Ph.D., head of canine genetics, Animal Health Trust, an English nonprofit looking for cures for companion animal diseases, and a member of the World Small Animal Veterinary Association (WSAVA) Hereditary Disease Committee (HDC), is urging veterinarians to educate dog breeders and dog owners about the perils of hereditary diseases. “The disease mutation that the DNA test is for is not the only mutation that a carrier has,” said Dr. Mellersch. She noted that most canines are carriers of at least 50 recessive mutations that can be passed along to offspring and potentially emerge later as an inherited disease. “If carriers are not bred from and only clear dogs used, then there is a risk that other mutations carried by these clear dogs will increase in frequency with the breed and new inherited disease could emerge,” Mellersch noted. She used Mendelian diseases, which are often caused by mutations in one gene and frequently breed-specific, to make her case. Primary open angle glaucoma that occurs in Shar Pei is a Mendelian disease—in fact, Mellersch and her colleagues have developed a DNA test for this painful inherited eye disease that causes blindness. “We ask vets to advise breeders to use DNA test results to avoid breeding clinically affected dogs and to reduce the frequency of mutation within a breed, over time, without damaging genetic diversity,” she said. Research has increased the number of resources available to veterinarians to help them educate others about the possible genetic fates awaiting the puppies their dogs sire or birth as well as helping those looking for a puppy to make an informed decision that doesn’t encourage the indiscriminate breeding of purebreds. One valuable tool in the fight against canine inherited diseases is the DNA database, created by the WSAVA’s HDC and funded by Mars Veterinary, a unit of Mars Petcare of Franklin, Tenn. Veterinarians worldwide can access the database for free at the WSAVA website. The site includes a finder for labs that do genetic testing, inherited diseases for select dog breeds are listed, as are canine inherited disorders and inherited disorders in animals and there are links to other organizations with an interest in canine genetics. Hereditary diseases will be a focus of the upcoming WSAVA World Congress in Copenhagen, Denmark, Sept. 25 to 28, 2017. “The greatest challenge we face is that of educating the … public that they should be mindful of hereditary disease when choosing a puppy and should seek out those whose breeders have had the appropriate DNA tests and clinical screens,” Mellersch said.
