Folded into every dog’s double helix—39 chromosomes containing about 2.5 billion base pairs of DNA—are clues to that dog’s current and future health risks. The more we learn about the canine genome, the more clearly these clues can be deciphered.
For centuries, people have deliberately bred dogs for dozens of purposes, from practical to decorative. The more closely a line of dogs hewed to the desired purpose, the more focused the breeding became. Consequently, genetic glitches that might’ve been lost in the crowd were amplified, resulting in the more than 350 inherited canine diseases currently known to exist.
One of those glitches with a far-reaching effect was highlighted by science writer Jane Brackman in an article she wrote for The Bark: “A mutation that probably originated in a single generic herding dog who lived in Great Britain in the mid-1800s … is responsible for sensitivity to several modern medicines, ranging from ivermectin (a common ingredient in heartworm preventives) to anticancer agents such as vincristine. These adverse drug responses can cause illness or death in the breeds that harbor the mutation.” More than 10 different breeds are affected, with Collies at the greatest statistical risk (over 70% of those tested).
And the list goes on. Flat-faced dogs are commonly known to have breathing and eye problems, and low-slung types are prone to intervertebral disc disease. Exercise-induced collapse and various cancers also have strong genetic components. Researchers associated with the University of Missouri College of Veterinary Medicine’s Canine Genetic Diseases Network have found mutations responsible for several inherited diseases in purebred dogs, including degenerative myelopathy, glaucoma and lens luxation, and cerebellar ataxia.
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So, what does all this mean in terms of practical application to our dogs’ health? First and foremost, it means that—once we know what’s in the mix of our mixed-breed dogs—we can be on the lookout for breed-specific health concerns. If we know that our dog has, say, Doberman in her background, we can be alert for the heart conditions Dobies are known to develop. Genes aren’t destiny—not all dogs who carry a gene for a disease will be affected by it—but, as the proverb notes, “forewarned is forearmed.”