Health & Testing
Degenerative Myelopathy in Dogs: What DM Means for Breeders and Buyers
Degenerative Myelopathy is the canine equivalent of ALS — progressive, incurable, and devastating. Here's what breeders and buyers must know about the SOD1 test.
March 25, 2024 · 5 min read
What Is Degenerative Myelopathy?
Degenerative Myelopathy (DM) is a progressive neurological disease caused by degeneration of the white matter in the spinal cord. It typically begins as hindlimb weakness and instability and progresses to paralysis and eventually affects respiratory function. DM is very similar in mechanism to Amyotrophic Lateral Sclerosis (ALS) in humans. There is no effective treatment or cure — only supportive care.
The SOD1 Gene and DM
Most canine DM is linked to a mutation in the SOD1 gene. Two known variants (SOD1A and SOD1B) are associated with DM in different breeds. Yorkshire Terriers are specifically associated with the SOD1A mutation. German Shepherd Dogs, Boxers, Pembroke Welsh Corgis, and many other breeds are also affected.
Understanding the Test Results
The DM test is different from most recessive disease tests because penetrance is incomplete — not all at-risk dogs (SOD1/SOD1) develop clinical DM. The test results:
- Clear (N/N): No risk. Cannot pass the variant.
- Carrier (N/SOD1): Unlikely to be affected but carries the variant. Can pass to offspring.
- At Risk (SOD1/SOD1): At significantly elevated risk of developing DM. May or may not develop clinical signs — but should not be bred.
At Star Struck Puppies
We include DM testing as part of our standard DNA panel for all breeding Yorkies and Biewer Terriers. Our goal is to eliminate the at-risk genotype from our breeding program within two generations by selecting clear or carrier dogs as breeding partners to at-risk carriers, gradually phasing out the at-risk genotype.