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Degenerative Myelopathy (DM)
Canine degenerative myelopathy (also known as chronic degenerative radiculomyelopathy) is a progressive disease of the spinal cord in older dogs. The disease has an insidious onset from about 7 years of age and is characterized by a loss of the myelin sheaths and axons of the cervical and lumbal spinal cord. This results in a loss of coordination (ataxia) in the hind limbs, leading to paralysis.
The mutated gene responsible for DM has been found in German Shepherd Dogs and is a major risk factor for the develoment of the disease. It is an Autosomal Recessive Trait.
• Weakness in the hind end
• Toe nail wear in the hind feet
• Slow reflexes in the hind feet and legs
• Trouble getting up
• Loss of coordination in the hind legs
• Loss of muscle mass in the hind end
• Limp tail
• Dragging one foot
• Trouble holding position to defecate
There is a test to determine if an animal has the mutated gene for DM, done by
Laboklin Laboratories, 125 Northenden Road, Manchester, M33 3HF Tel. 0161 282 3066
It is test No. 8158D and costs £75, with results in 7 working days.
A form can be downloaded from their website : www.laboklin.co.uk
The test consists of a cheek swab (using something similar to a Q-tip to swab the inside of the cheek to submit for testing and sent free of charge). The test checks for the mutated gene that will tell if your dog may be affected by degenerative myelopathy, if it is a carrier, or if it is unaffected.
The results are:
Normal / Normal (N/N) - this means your dog does not have the mutated strain and it will not develop degenerative myelopathy. (clear)
Normal / Abnormal (N/A) - this means your dog is a carrier of the gene but will not develop degenerative myelopathy. (carrier)
Abnormal / Abnormal (A/A) - this means that your dog is affected with degenerative myelopathy and may develop degenerative myelopathy (affected).
Not all dogs with A/A results will develop DM.
Breeding risks for degenerative myelopathy can be calculated using the Punnett Square:
• If both parents are clear (N/N) then all of the puppies will be clear
• If one parent is a carrier (N/A) &one is clear (N/N) then roughly 50% of the puppies will be clear & 50% will be carriers
• If both parents are carriers (N/A) then roughly 25% will be clear (N/N), 50% will be carriers (N/A), & 25% will be affected (A/A)
• If one parent is clear (N/N) & one parent is affected (A/A) then all puppies will be carriers (N/A)
• If one parent is a carrier (N/A) & one is affected (A/A) then roughly 50% of puppies will be carriers (N/A) & 50% will be affected (A/A)
• If both parents are affected (A/A) then all puppies will be affected (A/A)