Canine Degenerative Myelopathy
Canine degenerative myelopathy (CDM; also known as chronic degenerative radiculomyelopathy) is a neurological disease common in German Shepherds, Welsh Corgis, and several other breeds. The disease is chronic and progressive, and can result in lameness in the animal and eventually may lead to extensive paralysis of the back legs. The animal could be crippled within a few months, or may survive up to 3 years. Under any scenario, the disease is debilitating for the animal, severely hampers the quality of life, culminates in euthanasia, and is devastating for pet owners and breeders alike.
Signs of Canine Degenerative Myelopathy
The disease usually manifests between the ages of seven and fourteen and initially affects the back legs and causes muscle weakness and loss, and lack of coordination. These cause a staggering effect that may appear to be arthritis. The dog may scuff its one or both rear paws when it walks. This scuffing can cause the nails of one foot to be worn down.1
Degenerative myelopathies in Ibizan Hounds, Labrador Retrievers and terriers are autosomal recessive defects with early ages of onset (less than 1 year).4
Associations between low levels of certain vitamins (Vitamin B12 and E) have been made in some German Shepherd Dogs with degenerative myelopathy. There is also some evidence to suggest the immune-mediated basis for this disease.2
Analysis of cerebrospinal fluid (CSF) is part of a routine clinical workup in veterinary patients when neurological disease is suspected. However, knowledge of particular protein markers of disease in CSF is limited. The concentration of myelin basic protein (MBP) in CSF is used as a biochemical marker in humans to evaluate demyelinating lesions in the central nervous system (CNS). The MBP ELISA test has potential as a supplemental test of CSF to diagnose demyelinating disorders in dogs.5
Treatment of Canine Degenerative Myelopathy
CDM is a chronic condition that cannot be cured, though it may be possible to maintain the dog's quality of life for a short time through a proper program of exercise and nutrition. Exercise has been recommended to maintain the dog's ability to walk, and physiotherapy may prolong the length of time that the dog remains mobile and increase survival time, but the ultimate outcome is not favorable.1
Dogs with this condition benefit from a wide range of resourceful home care items such as runner rugs for a slippery floor; ramps for the stairs, bed and car; slings for assistance while walking; chest and rump lifts to help larger dogs stand up; canvas suspension hammocks; wheel carts, soft bedding, and so on.3
There is evidence that there is an association between DM symptoms and the mutation in the following breeds: Bernese Mountain Dog, Boxer, Cardigan Welsh Corgi, Chesapeake Bay Retriever, German Shepherd Dog, Kerry Blue Terrier, Pembroke Welsh Corgi, Rhodesian Ridgeback, Standard Poodle.6
There are still no proven effective therapies to halt or slow progression of CDM. Although not approved by the U.S. Food and Drug Administration (FDA), aminocaproic acid (EACA) and n-acetylcysteine (NAC) may slow the progression, but this treatment is still experimental and controversial.1
Considering the debilitating nature of the disease and the lack of proven therapies, the identification of genetic markers to permit the identification of animals that are predisposed to developing CDM would be very beneficial to breeders and pet owners alike 11].
A free DNA test is offered for dogs who have been diagnosed with CDM at the University of Missouri. Dogs must meet certain criteria to be eligible for a free DNA test.
References:
1. Prediction and diagnosis of canine degenrative myelopathy. J. Coats, K. Linblad-Toh, C. Wade, G. Johnson. US2009239225 (A1) 2009-09-24
2. A practical guide to canine and feline neurology. Curtis W. Dewey, Anton G. Hoffman, Carol Rudowsky
3. Canine and feline geriatric oncology: honoring the human-animal bond. Alice Villalobos, Laurie Kaplan
4. The genetics of the dog. Anatoly Ruvinsky, Jeff Sampson
5. Measurement of myelin basic protein in the cerebrospinal fluid of dogs with degenerative myelopathy. Oji T, Kamishina H, Cheeseman JA, Clemmons RM. In: Vet Clin Pathol. 2007 Sep;36(3):281-4
6. Degenerative Myelopathy Research. Ongoing and Additional Research University of Missouri-Columbia, College of Veterinary Medicine.
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