Congenital myasthenic syndrome is an inherited neuromuscular disease observed in the Jack Russell Terrier. Affected puppies appear normal until 6 weeks of age, then gradually develop generalized muscle weakness, walking briefly for 10 to 15 steps before stopping or lying down. Treatment with anticholinesterase drugs leads to temporary improvement, but resistance to the treatment often requires euthanasia.

In the Jack Russell Terrier, congenital myasthenia is most commonly caused by the 729dup mutation. However, under the breeding regulation of the Flemish government, it is the 1508dup mutation that must be tested for in both the Jack Russell Terrier and the American Staffordshire Terrier. This test specifically detects the 1508dup mutation.

Transmission

Breed

American Staffordshire Terrier (Amstaff), Jack Russell Terrier, Smooth Fox Terrier, Heideterrier