The clinical signs of X-linked myotubular myopathy can be seen in puppies as young as 10 to 19 weeks of age with early signs of muscle atrophy being apparent earlier in some cases. Pelvic limb weakness is typically observed as one of the first signs. Affected dogs also lack patellar reflexes. X-linked myotubular myopathy is characterized by rapidly progressing muscle weakness and muscle atrophy. Affected dog won’t be able to rise and move unassisted within a few weeks of the onset of clinical signs and may also have difficulties chewing and swallowing. There is no cure for the condition.

Affected puppies are usually euthanized on welfare grounds because of the severity of the condition.

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 X-linked recessive, meaning the genetic variant is found on the X chromosome. Given males only have one X chromosome, a single affected copy will increase the risk of being diagnosed with the disorder. Females typically require two copies to be at an elevated risk for full clinical signs but are not generally seen due to the poor prognosis for affected males. Use of dogs with one or two copies of the variant is not recommended for breeding as there is a risk that the resulting litter will contain affected puppies. Please note: It is possible that clinical signs similar to the ones caused by this variant could develop due to a different genetic or clinical cause.