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Congenital Myasthenic Syndrome (Discovered in the Golden Retriever)

Congenital myasthenic syndromes (CMSs) are a group of inherited neuromuscular disorders. The CMS in Golden Retrievers is characterized by generalized muscle weakness and abnormal gait. The causative gene for CMS in Golden Retrievers is COLQ.

Found in

1 in 5,000 dogs

in our testing

Key Signs

Generalized weakness, Abnormal gait, Exercise intolerance, Collapse

Age of Onset

0 to 2 yrs

Juvenile onset


Autosomal Recessive

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.

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 CMS

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 CMS

The first clinical signs of congenital myasthenic syndrome in Golden Retrievers can be observed in 6-8 weeks old puppies. Affected puppies show severe exercise-induced muscle weakness. Affected puppies have abnormal gait that becomes shorter and stiffer with continued walking to the point that the puppy will lie down. Muscle weakness is caused by a deficiency of acetylcholinesterase which is essential for proper muscle contraction.

Upon initial observation of clinical signs, affected dogs should be closely monitored to assess welfare and devise a supportive care treatment plan. Due to the progressive nature of the disease, affected dogs are often euthanized for welfare reasons by 1 year of age.

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 disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to occur. A carrier dog with one copy of the CMS mutation can be safely bred with a clear dog with no copies of the CMS mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the CMS mutation. 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 disease signs similar to the ones caused by the CMS mutation could develop due to a different genetic or clinical cause.

Technical Details

Variant G>A
Chromosome 23
Coordinate 27,175,559

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Tsai, K. L., Vernau, K. M., Winger, K., Zwueste, D. M., Sturges, B. K., Knipe, M., … Shelton, G. D. (2020). Congenital myasthenic syndrome in Golden Retrievers is associated with a novel COLQ mutation. Journal of Veterinary Internal Medicine, 34(1), 258–265. View the article