Genetics Behind the Degenerative Myelopathy of German Shepherds

The DNA mutation causing degenerative myelopathy is now known.
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If your German shepherd is diagnosed with degenerative myelopathy, the one consolation is that you finally know what's wrong with your dog. Your vet might have initially treated your pal for more common disorders, but your dog didn't improve. While there's no cure, there's now a genetic test for the disease.

Degenerative Myelopathy

Degenerative myelopathy in canines is similar to multiple sclerosis in people. It's also been compared to Lou Gehrig's disease, or amyotrophic lateral sclerosis. While the disease affects other breeds, it's so common in German shepherds that it's also known as German shepherd degenerative myelopathy. The white matter in the dog's spinal cord deteriorates, meaning his nervous system can no longer send movement commands between his brain and his back legs. The hind leg nerves can't send sensory information back to the brain.


Generally occurring in older dogs, you might first mistake the early signs of degenerative myelopathy for arthritis. Your dog becomes increasingly unsteady on his back end. He starts dragging his rear paws, falling down and rising with difficulty. The situation becomes progressively worse. Affected dogs are often paralyzed in the hind end within a few months of the onset of symptoms. There's no cure, but physical therapy, as well as a canine wheelchair to support the back end, can aid mobility. Most afflicted dogs are euthanized once they can no longer move. The only good news is that the condition doesn't appear to be painful.

Superoxide Dismutase 1

First identified in 2009, superoxide dismutase 1 is the genetic mutation in the German shepherd's DNA that causes degenerative myelopathy. It's an inherited recessive issue. If a dog carries the mutation and is bred to a non-carrier, the mutation passes on to 50 percent of their puppies. If two carriers breed, 25 percent of their puppies will carry two copies of the mutated gene, meaning they're much more likely to develop degenerative myelopathy.


You can have your dog tested for the gene mutation for degenerative myelopathy. The test is simple. You swab your dog's cheek and gums with ordinary cotton swabs, then send the samples to a genetic testing laboratory. This test identifies those dogs with two normal copies of the gene, who aren't affected; those carrying one normal and one mutated gene, becoming carriers; and those with two mutated copies of the gene, who are at much higher risk of developing the disease. If your dog does turn out to have two mutated copies, don't despair. That only means he's at increased risk, not that he'll definitely come down with the condition. However, you shouldn't breed him.

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