What is Centronuclear Myopathy?
Centronuclear Myopathy (CNM) is genetic muscle wasting disease typified by an early onset of the disease in young dogs. The disease is usually apparent very early in the dog’s life (by about 1 month old) although affected puppies are indistinguishable from their normal littermates at birth. Muscle weakness and wasting is first apparent in the larger muscles of the hind limbs but eventually affects other muscles in the body.
Genetics of Centronuclear Myopathy
Centronuclear Myopathy (CNM) is an inherited disease with an autosomal recessive mode of inheritance meaning that the dog must inherit a faulty copy of the gene responsible from each parent to be affected. The gene responsible in this case is the PTPLA gene where a single missense mutation results in the production of defective proteins.
What is the severity of Centronuclear Myopathy?
Centronuclear Myopathy is extremely severe as the dogs affected will have a poor quality of life and see a premature end to their life. The disease has no cure and owners normally opt for an early euthanasia for affected dogs to prevent further suffering by the dog.
What are the symptoms of Centronuclear Myopathy in dogs?
Symptoms of Centronuclear Myopathy often show very early in the dog’s life and by the time the puppy is a few weeks old they are showing signs that something is wrong. Some dogs have not displayed symptoms until they are up to 6 months old but this is definitely the exception rather than the rule. Affected puppies are smaller, weaker, are unstable standing up and have a very low tolerance for exercise compared to their litter mates. They will also have difficulty eating and a generalised muscle weakness. The muscle weakness becomes worse over time.
Diagnosis of Centronuclear Myopathy in dogs
Excluding infectious causes such as Neospora caninum and Toxoplasma gondii is often the first step in diagnosing Centronuclear Myopathy but a definitive diagnosis can only be achieved via DNA testing. This is the same DNA test used to identify clear and carrier dogs for the disease.
Treatment and prognosis for dogs with Centronuclear Myopathy
While there is currently no way to stop the degeneration of muscle tissue with Centronuclear Myopathy, some vets have reported varying degrees of success with supportive medications such as L-carnitine, co-enzyme Q10 and vitamin B compounds in slowing down the disease. Progression of the disease can plateau at about 1 year old and dogs may theoretically have a normal lifespan, they will have life-long medical conditions and difficulties. DNA testing for this condition in breeding dogs is the best way to prevent future generations of dogs from being affected by Centronuclear Myopathy.
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