Congenital Myasthenic Syndrome, CMS

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 3-4 months of age.

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

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

Talk to your vet about your dog’s CMS result so you can plan appropriate monitoring and care.

Avoid intense or prolonged exercise, as overexertion can worsen weakness or fatigue.

Provide a calm, stable routine with gentle activity to help maintain mobility and prevent stress.

With careful management and regular check-ins, many dogs with CMS can live comfortable lives.

This mutation was first described in Old Danish Pointing Dogs.

Penetrance: 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

CHAT (Exon 6)

Inheritance type

recessive

Clinical category

Neuromuscular

Citations

1. Proschowsky et al 2007

• Old Danish Pointing Dog