Congenital Myasthenic Syndrome, CMS


This is a non-progressive disease characterized by episodes of exercise intolerance and weakness

  • Signs and symptoms

    Affected puppies can usually play or run for up to a half hour, after which their strides get progressively shorter and the dog collapses. After resting, dogs show no ill effects.

    Signs first appear in puppies, typically between 3-5 months of age.

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  • Diagnosis

    Genetic testing, blood work, neurological tests, and clinical signs can be used to diagnose this condition.

  • Treatment

    CMS is a lifelong condition that thankfully does not progress; affected dogs typically enjoy a good quality of life besides their exercise intolerance.

  • What to do if your dog is at risk


    • Minimizing intense exercise may help reduce clinical signs. Please follow the recommendations from your veterinarian.

  • Genetic Information

    This mutation was first described in Labrador Retrievers.

    This disease is inherited in an autosomal recessive manner, meaning that affected dogs must have two copies of the mutation to show clinical signs.

    Gene names:

    COLQ (Exon 14) ‐ chr

    Inheritance type:


  • Breeds affected

    This health condition affects the following breeds

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