DM is a progressive disease of the spinal cord in older dogs. The breeds most commonly affected include German Shepherds, Welsh Corgis, Irish Setters, and Chesapeake Bay Retrievers. The disease has an insidious onset typically between 8 and 14 years of age.
Testing for DM helps breeders eliminate this disease. Unfortunately, not all breeders test their dogs. To help you understand how a dog gets DM, here’s what testing shows.
A corgi puppy gets two genes, one from each parent. The genes determine whether or not they are at risk of getting DM. After a dog is tested, it is rated as either an A, B, or C.
What the ratings mean
An “A” dog means it has two good genes and will NOT get DM.
A “B” dog means, though it has one good gene and one bad gene, it too will NOT get DM and makes a great pet.
A “C” dog means it is at risk of getting DM.
In summary, you should never buy a dog whose parent pairs are either: B/B or B/C unless the puppy has been tested and verified it is not at risk. And NEVER buy a dog whose parent pair is C/C.