Muscular Dystrophy (Discovered in the Norfolk Terrier)

This form of Muscular Dystrophy is a disease of progressive muscular weakness, respiratory problems, and cardiomyopathy (heart disease).

Key Signs

Progressive muscular weakness, Respiratory dysfunction, Cardiomyopathy

Age of Onset

0 to 2 yrs

Juvenile onset

Inheritance

X-linked Recessive

For X-linked recessive disorders, the genetic variant is found on the X chromosome. Female dogs must have two copies of the variant to be at risk of developing the condition, whereas male dogs only need one copy to be at risk. Males and females with any copies of the variant may pass the disorder-associated variant to their puppies if bred.

Likelihood of the Condition

High likelihood

At risk dogs are highly likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a dog with Muscular Dystrophy

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.

For Veterinarians

Here’s what a vet needs to know about Muscular Dystrophy

Clinical signs of the disease appear at a young age. Affected puppies show progressive muscular weakness, respiratory problems, and have cardiomyopathy. The prognosis of the disease is poor.

Glucocorticoid therapy and dantrolene therapy may provide temporary improvement. However, because of the severity of the clinical signs, affected puppies are usually euthanized at a young age on welfare grounds.

For Breeders

Planning to breed a dog with this genetic variant?

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. 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.

Technical Details

Gene	Dystrophin
Variant	Deletion
Chromosome	X
Coordinate	27,606,021

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Jenkins, C. A., & Forman, O. P. (2015). Identification of a novel frameshift mutation in the DMD gene as the cause of muscular dystrophy in a Norfolk terrier dog. Canine Genetics and Epidemiology, 2(1), 2–5. View the article

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