Myotubular Myopathy is sex-linked inherited muscle disease that occurs in Labrador Retriever and Rottweiler. Symptoms are similar to Centronuclear Myopathy (CNM) / Hereditary Myopathy.
Affected puppies appear normal at birth but they start showing symptoms between 7 and 19 weeks of age. Symptoms include progressive skeletal muscle atrophy, muscle weakness especially in the hind limbs, small stature compared to unaffected littermates, puppies can walk with short choppy strides, collapsing after few strides, difficulty eating due to weakness in mastication muscles, which may lead to dropped jaws, hoarse bark.
The disease progresses rapidly and puppies become unable to stand or raise their heads by 3-4 weeks after the start of the symptoms.
Affected dogs are usually euthanized between 15-26 weeks of age.
Due to the X Linked recessive mode of inheritance, males can either be clear or affected, where as females can be clear, carriers or affected. Females are rarely affected because affected males are usually euthanized at young age. The disease is primarily found in males. Testing enables breeders to identify clear, carrier and affected dogs and help in reducing the occurrence of the disease.
XLMTM is considered rare and we currently have no information about its prevalence in the UK.