What is Degenerative Myelopathy (DM)?

Degenerative myelopathy is a progressive disease of the spinal cord in older dogs. The disease has an insidious onset typically between 8 and 14 years of age. It begins with a loss of coordination (ataxia) in the hind limbs. The affected dog will wobble when walking, knuckle over or drag the feet. This can first occur in one hind limb and then affect the other. As the disease progresses, the limbs become weak and the dog begins to buckle and has difficulty standing. The weakness gets progressively worse until the dog is unable to walk. The clinical course can range from 6 months to 1 year before dogs become paraplegic. If signs progress for a longer period of time, loss of urinary and fecal continence may occur and eventually weakness will develop in the front limbs. Another key feature of DM is that it is not a painful disease.

This test is available for all dog breeds. Initially, this inherited recessive disorder was thought to only affect German Shepherd Dogs; however, degenerative myelopathy has been recently diagnosed in several other dog breeds including the following:

• Cardigan Welsh Corgi
• Boxer
• Poodle
• Golden Retriever

The 3 possible genotypes for degenerative myelopathy:

• CLEAR (those having 2 copies of the normal allele and appear to be normal).
• CARRIER (those having 1 copy of the normal allele and 1 copy of the mutation but appear to be normal).
• AT RISK (those having 2 copies of the mutation and will likely show clinical signs.)

 
Explanation of DM DNA results:
 
NORMAL (N/N)
This dog is homozygous N/N, with two normal copies of the gene. In the seven breeds studied at the University of Missouri in depth so far, dogs with test results of N/N (Normal) have never been confirmed to have DM. This dog can only transmit the normal gene to its offspring, and it is unlikely that this dog or its offspring will ever develop DM.

CARRIER (A/N)

This dog is heterozygous A/N, with one mutated copy of the gene and one normal copy of the gene, and is classified as a carrier. In the breeds studied at the University of Missouri in depth so far, dogs with test results of A/N have never been confirmed to have DM. While it is highly unlikely this dog will ever develop DM, this dog can transmit either the normal gene or the mutated gene to its offspring. 

AT RISK (A/A)

This dog is homozygous A/A, with two mutated copies of the gene, and is at risk for developing Degenerative Myelopathy (DM). The research has shown that all dogs in the research study with confirmed DM have had A/A DNA test results, however, not all dogs testing as A/A have shown clinical signs of DM. DM is typically a late onset disease, and dogs testing as A/A that are clinically normal may still begin to show signs of the disease as they age. Some dogs testing A/A did not begin to show clinical signs of DM until they were 15 years of age. Research is ongoing to estimate what percentage of dogs testing as A/A will develop DM within their lifespan. At this point, the mutation can only be interpreted as being at risk of developing DM within the animal’s life. For dogs showing clinical signs with a presumptive diagnosis of DM, affected (A/A) test results can be used as an additional tool to aid in the diagnosis of DM. Dogs testing At-Risk (A/A) can only pass the mutated gene on to their offspring.

Where can I order a DM test kit?

DDC Veterinary and the OFA are the two organizations we recommend for DM testing. We use and highly recommend, DDC Veterinary. Test kits are only $58 and they get the results back to you very quickly. The OFA's kits are a little more expensive ($65) and it can take a while to get your results. But, one plus to using the OFA versus DDC is all results are posted to an online searchable database.

DDC Veterinary DM Test Kit Page

OFA DM Test Kit Page


The information above is courtesy Degenerative Myelopathy - Disease Basics, DDC Veterinary and the OFA.

You can read more information on Degenerative Myelopathy (DM) by clicking here.