Canine degenerative myelopathy , also known as chronic degenerative radiculomyelopathy , is an incurable, progressive disease in the spinal cord of the canine that is similar in many ways to amyotrophic lateral sclerosis (ALS). Onset is usually after 7 years of age and is most commonly seen in German shepherd dogs, Pembroke Welsh corgi, and dog fighters, although this disorder is strongly associated with gene mutations in SOD1 found in 43 breeds in 2008, including ferris wire terrier, Chesapeake Bay retriever , Rhodesian ridgeback, and Welsh Corgi Cardigan. Progressive weakness and lack of limbs are often the first signs seen in affected dogs, with progress from time to time to complete paralysis. Myelin is the insulating sheath around the neurons in the spinal cord. One of the proposed causes of degenerative myelopathy is that the immune system attacks this envelope, breaking it down. This results in loss of communication between the nerves in the lower body of the animal and the brain.
Video Canine degenerative myelopathy
Test
The Orthopedic Foundation for Animals has a DNA saliva test to filter out the mutated genes that have been seen in dogs with degenerative myelopathies. Now that the test is available, the disease can be bred from a high-strength breed. This test is only recommended for breeds that have a tendency, but can be done on DNA from any dog ​​in samples collected through the insertion of the inside of the animal cheeks with sterile cotton or via venipuncture.
The test determines whether a copy of the SOD1 mutation is present in the proposed DNA sample. This should be interpreted with caution by the veterinarian in combination with animal clinical signs and other lab test results.
The reported results are:
- Normal/Normal (N/N, or 'clear'): The dog has no mutation and it is highly unlikely to develop degenerative myelopathy. There are cases where the dog tested clearly found to have DM on necropsy. This information is given to Dr. Keller from OFA. Dr. Coates does necropsy. It is important to note the OFA statement on their website stating "Recent evidence indicates that there are other causes of DM in some breeds".
- Normal/Abnormal (N/A or 'carrier'): The dog has one copy of the mutated gene (heterozygous) and is a carrier but will not have degenerative myelopathy even though there have now been several cases of heterozygous carriers developing DM. It is possible to pass mutations to the offspring. A thorough examination of the dog's pedigree and DNA testing should be performed before breeding the dog with these results. Abnormal/Abnormal (A/A or 'At Risk'): The dog has two copies (homozygous) for mutation and is at risk for degenerative myelopathy.
Maps Canine degenerative myelopathy
Genetics
Breeding risk for degenerative myelopathy can be calculated by using Punnett Square:
- If both parents are clear (N/N) then all puppies will become clear.
- If one parent is an introductory (N/A) and one clear (N/N) each puppy has a 50% chance of becoming clear and 50% likely to be an introduction.
- If both parents are introductory (N/A) each puppy has a 25% chance of being clear (N/N), 50% A)
- If one parent is clear (N/N) and one parent is affected (A/A) then all puppies will be carriers (N/A)
- If one parent is an operator (N/A) and one at risk (A/A) each puppy has 50% chance of being a carrier (N/A) and 50% )
- If both parents are threatened (A/A) then all puppies will be affected and carrier (A/A)
Symptoms
Degenerative myelopathy initially affects the hind legs and causes muscle weakness and loss, and lack of coordination. This causes a surprising effect that may appear to be arthritis. Dogs can drag one or both legs back while walking. This drag can cause one toe nails to become tired. This condition can cause extensive back leg paralysis. As disease develops, animals may exhibit symptoms such as incontinence and have great difficulty with balance and walking. If allowed to develop, animals will show involvement of the front limbs and widespread muscle atrophy and paralysis. Finally, cranial nerve or respiratory muscle involvement requires euthanasia or long-term palliative care.
The development of this disease is generally slow but very varied. The animal can be paralyzed within a few months, or it can survive for three years or more.
Cause
The etiology of this disease is unknown. Recent studies have shown that mutations in the SOD1 gene are a risk factor for developing degenerative myelopathies in some breeds. Mutation in SOD1 is also associated with familial amyotrophic lateral sclerosis (Lou Gehrig's disease) in humans. More than 100 mutations of the SOD1 gene are involved in familial familial familial amyotrophic (ALS) lateral sclerosis, and pathologic pathologic lesions of ALS are similar to dog DM, making DM dogs a potential animal model of ALS. The cause of spinal cord dysfunction is known to be excluded before receiving a diagnosis of degenerative myelopathy; disc disease (bulge) or spinal cord tumor can cause spinal cord compression with signs similar to degenerative myelopathy.
Treatment
Degenerative myelopathy is an irreversible progressive disease, which is currently incurable. No treatment is clearly shown to stop or slow the progression of DM.
Exercise
Source of the article : Wikipedia
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