Introduction
If your dog is showing signs of hind limb weakness or wobbliness, it could be more than just aging—it might be a serious neurological condition called Degenerative Myelopathy (DM). This progressive spinal cord disease can lead to paralysis and is often misdiagnosed due to its similarity to other spinal disorders.
Thanks to groundbreaking research by teams at the University of Missouri and the Broad Institute of MIT/Harvard, a genetic mutation linked to DM has been identified. This discovery has led to the development of a DNA test that helps breeders and pet owners understand their dog’s risk for this debilitating disease.
Key Points
- A DNA mutation in the SOD1 gene is a major risk factor for Degenerative Myelopathy.
- A new DNA test identifies dogs as clear, carriers, or genetically at risk.
- Dogs with two mutated copies of the gene are at higher risk but may not always develop DM.
- Several breeds—including Boxers, Corgis, Ridgebacks, and Retrievers—have high mutation rates.
- Testing helps breeders reduce DM risk in future generations.
Challenge Background
Degenerative Myelopathy is a progressive, adult-onset spinal cord disease that causes weakness in the hind limbs and eventually leads to paralysis. Because its symptoms mimic other spinal conditions, DM is often misdiagnosed. Currently, a definitive diagnosis is only possible postmortem through microscopic examination of the spinal cord. This diagnostic limitation has made it difficult for veterinarians and owners to manage the disease effectively.
The Breakthrough
Researchers led by Drs. Gary Johnson and Joan Coates (University of Missouri) and Drs. Claire Wade and Kerstin Lindblad-Toh (Broad Institute) identified a mutation in the SOD1 gene that significantly increases the risk of developing DM. This discovery was made possible through funding from breed clubs and the AKC Canine Health Foundation.
The resulting DNA test can determine whether a dog:
- Has two normal copies of the gene (clear)
- Has one normal and one mutated copy (carrier)
- Has two mutated copies (genetically affected)
Importantly, not all genetically affected dogs develop DM, indicating that other risk factors may influence disease onset. Ongoing research aims to identify these additional factors and understand why some dogs remain symptom-free.
Impact & Next Steps
This genetic test empowers breeders and owners to make informed decisions that could reduce the incidence of DM over time, especially in breeds with high mutation frequencies. By selectively breeding dogs that are clear or carriers, the mutation can be gradually phased out over generations.
Future research will focus on:
- Identifying additional genetic or environmental risk factors
- Understanding why some genetically affected dogs remain healthy
- Expanding breed-specific data to guide testing strategies
Dog owners can contribute by submitting blood samples for testing, helping researchers refine their understanding of DM and improve canine health outcomes.
