Causes
The etiology of this disease is unknown. Recent research has shown that a mutation in the SOD1 gene is a risk factor for developing degnerative myelopathy in several breeds. Mutations in SOD1 are also associated with familial amyotrophic lateral sclerosis (Lou Gehrig's disease) in people. However, it has been discovered that 1 German Shepherd Dog that tested Clear (N/N) was found to have DM, upon necropsy. This German Shepherd Dog was found to be homozygous for the normal form of the SOD1 gene. German Shepherd Dog Myelopathy (aka GSDM) is its own unique disease. While ALS (amyotrophic lateral sclerosis) does not involve sensory loss, German Shepherd Dog Myelopathy involves complete sensory loss. Therefore, German Shepherd Dog Myelopathy is not the common form of DM which affects other breeds, which is the type of Myelopathy for which this test was developed.
Known causes of spinal cord dysfunction should be excluded before accepting the diagnosis of degenerative myelopathy; disc disease (protrusions) or spinal cord tumors can cause compression of the spinal cord with similar signs to degenerative myelopathy.
Read more about this topic: Canine Degenerative Myelopathy