Canine Degenerative Myelopathy (DM)
Degenerative Myelopathy (DM) 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. Although any dog can be tested for DM, it is possible that the genetic background that predominates in some breeds prevents the development of symptoms even in dogs testing affected (at risk). At this time the required evidence of association between the genetic mutation and actual spinal cord evaluations has only been proven in the breeds listed.
Please see http://www.offa.org/dnatesting/dmexplanation.html and http://www.caninegeneticdiseases.net/DM/ancmntDM.htm for additional information on DM diagnosis.
American Eskimo Dogs
Bernese Mountain Dog
Cardigan Welsh Corgi
Chesapeake Bay Retrievers
Coton De Tulear
German Shepherd Dog
Kerry Blue Terriers
Pembroke Welsh Corgis
Soft Coated Wheaten Terriers
Wire Fox Terrier
A (CLEAR/NORMAL): These dogs have two normal copies of DNA. Among the hundreds of dogs studied to date at the University of Missouri, only two dogs with test results of ‘CLEAR/NORMAL’ have been confirmed to have DM.
B (CARRIER/NOT AFFECTED): These dogs have one copy of the mutation and one normal copy of DNA. Carriers are far less likely to develop DM however; a few cases to date of DM have been confirmed in a small number of carrier dogs.
C (AT RISK/AFFECTED): These dogs have two copies of the mutation and will likely develop DM during their lifetime. Although many dogs tested to date typed as ‘AT RISK/AFFECTED’ have been clinically confirmed DM, recent evidence suggest that there are other causes of DM in some breeds. In addition, not all dogs testing as ‘AT RISK/AFFECTED’ have shown clinical signs of DM. Research is ongoing to estimate what percentage of dogs testing as ‘AT RISK/AFFECTED’ will develop DM within their lifespan. At this point, the DM mutation can be interpreted as being ‘AT RISK’ of developing DM within the animal’s lifetime. For dogs showing clinical signs with a presumptive diagnosis of DM, ‘AT RISK/AFFECTED test results can be used as an additional tool to aid in the diagnosis of DM.