Myotonia Congenita in Brittany Spaniels

In myotonia congenita, a genetic abnormality affects how muscle cell membranes manage electrical signals, causing muscle fibers to remain contracted longer than normal after they're activated, rather than relaxing promptly. This produces a stiff, sometimes bunny-hopping or stilted gait that's often most noticeable after a dog has been resting and tends to ease somewhat once the dog has moved around for a bit, a pattern sometimes called a 'warm-up' effect.

Affected dogs may also show a generalized increase in muscle bulk, since the muscles are essentially working harder due to this abnormal contraction pattern. The condition itself doesn't typically cause pain, though the altered gait can look concerning to an owner unfamiliar with it.

Given how rare true myotonia congenita is, and how much more common conditions like hip dysplasia are in this specific breed, a vet exam is essential to distinguish between these possibilities rather than assuming the rarer diagnosis.

If you think your Brittany has myotonia congenita, the plan is three steps: write down what you have seen and when it started, book a veterinary appointment rather than waiting for the next flare, and take video of the behaviour or symptom before you go — the thing you are worried about rarely happens in the consulting room. Screening in the parents covers hip dysplasia, elbow dysplasia, progressive retinal atrophy.

What the vet visit should produce is a diagnosis and a written plan, not just reassurance: what is being ruled out, what the monitoring interval is, and which signs mean you come back sooner. Ask what the treatment costs across a year rather than per visit, because that is the number that decides whether you are managing this condition or reacting to it.

Between appointments, keep a short log — dates, what you saw, what changed. It is the single most useful thing an owner brings to a follow-up, and for myotonia congenita it is often what separates a clear pattern from a guess.