For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.
At risk dogs are highly likely to show signs of this disease in their lifetime.
Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.
Congenital Muscular Dystrophies are a group of inherited neuromuscular disorders. Clinical signs associated with Congenital Muscular Dystrophy, identified in the Staffordshire Bull Terrier, will be present by a few months of age in affected dogs. Signs may include poor body condition with generalized muscle atrophy, muscular weakness, decreased reflexes, a stiff and short-strided gait, reduced jaw mobility, decreased appetite, muffled bark and regurgitation. Mentation of affected dogs generally remains normal. The condition is chronic and progressive, leading to muscle fibrosis and atrophy as well as potential joint contractures, limb and spinal deformities, mobility difficulties, and exercise intolerance. Cardiomyopathy (heart disease) is often a clinical sign in humans affected with the disorder, but it is not yet known if this is experienced by dogs with the condition. Blood chemistry can show persistent, marked elevation in serum creatine kinase concentrations and mild-moderate increases in ALT. Electromyography results can appear abnormal with widespread spontaneous activity. Histopathology may show general signs of muscular dystrophy and endomysial fibrosis, and immunofluorescent staining for alpha 2 laminin will show an absence of staining.
The long-term prognosis for CMD is poor as the condition is progressive and treatment is limited to supportive care. Affected dogs experiencing difficulty with movement may require assistance with routine tasks. Assessment of cardiac involvement can be considered based on clinical signs present. Welfare should be closely monitored as the disorder progresses, with humane euthanasia often necessary for more severely affected dogs.
There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.
This disorder is autosomal recessive, meaning two copies of the variant are needed for a dog to be at an elevated risk for being diagnosed with the condition. A carrier dog with one copy of the Congenital Muscular Dystrophy (Discovered in the Staffordshire Bull Terrier) variant can be safely bred with a clear dog with no copies of the Congenital Muscular Dystrophy (Discovered in the Staffordshire Bull Terrier) variant. About half of the puppies will have one copy (carriers) and half will have no copies of the variant. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disorder signs similar to the ones associated with this CMD variant could develop due to a different genetic or clinical cause.
All coordinates reference CanFam3.1
Shelton, G.D., Minor, K.M., Thomovsky, S., Guo, L.T., Friedenberg, S.G., Cullen, J.N., Mickelson, J.R. (2022). Congenital muscular dystrophy in a dog with a LAMA2 gene deletion. J Vet Intern Med, 36(1), 279-284. View the article