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Muscular Dystrophy (Discovered in the Cavalier King Charles Spaniel)

Muscular Dystrophy is a severe disorder that causes muscle breakdown and weakness. DMD is characterized by a curve to the dog's back and a crouched posture. It typically affects males, although some females may also show some muscle weakness as well.

Key Signs

Muscle fibrosis, High serum creatine kinase concentration, Spinal curvature, Crouched posture, Thick tongue base, Excessive salivation

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

Duchenne muscular dystrophy results from dysfunction of the sarcolemma (cell membrane of muscle fiber cells) which causes degeneration and necrosis of muscle tissue. It is a progressive condition that eventually leads to muscle fibrosis (formation of excess fibrous connective tissue). First signs of disease, such as bunny-hopping gait, can be observed in eight to ten weeks old puppies. Affected puppies have a thick tongue base and are unable to open the mouth properly which causes eating difficulties and excess drooling. Duchenne muscular dystrophy is characterized by crouched posture caused by spinal curvature and bending of the back. Serum creatine kinase concentrations can be over 300 times higher than normal levels.

Treatment is supportive care. Humane euthanasia for affected puppies is often elected.

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 G>T
Chromosome X
Coordinate 26,956,239

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Kornegay, J. N., Bogan, J. R., Bogan, D. J., Childers, M. K., & Grange, R. W. (2011). Golden retriever muscular dystrophy (GRMD): Developing and maintaining a colony and physiological functional measurements. Methods in Molecular Biology (Clifton, N.J.), 709, 105–123. View the article

Cooper, B. J., Winand, N. J., Stedman, H., Valentine, B. A., Hoffman, E. P., Kunkel, L. M., Scott, M. O., Fischbeck, K. H., Kornegay, J. N., Avery, R. J., Williams, J. R., Schmickel, R. D., & Sylvester, J. E. (1988). The homologue of the Duchenne locus is defective in X-linked muscular dystrophy of dogs. Nature. View the article

Sharp, N. J. H., Kornegay, J. N., Van Camp, S. D., Herbstreith, M. H., Secore, S. L., Kettle, S., … Bartlett, R. J. (1992). An error in dystrophin mRNA processing in golden retriever muscular dystrophy, an animal homologue of Duchenne muscular dystrophy. Genomics, 13(1), 115–121. View the article

Smith, B. F., Yue, Y., Woods, P. R., Kornegay, J. N., Shin, J. H., Williams, R. R., & Duan, D. (2011). An intronic LINE-1 element insertion in the dystrophin gene aborts dystrophin expression and results in Duchenne-like muscular dystrophy in the corgi breed. Laboratory Investigation, 91(2), 216–231. View the article

Walmsley, G. L., Arechavala-Gomeza, V., Fernandez-Fuente, M., Burke, M. M., Nagel, N., Holder, A., … Piercy, R. J. (2010). A duchenne muscular dystrophy gene hot spot mutation in dystrophin-deficient Cavalier King Charles Spaniels is amenable to exon 51 skipping. PLoS ONE, 5(1). View the article