Degenerative Myelopathy and the Papillon: When Weakness Does Not Hurt

Almost everything that makes a dog's back end unreliable hurts. Arthritis hurts. A torn cruciate hurts. A herniated disc pressing on nerve roots hurts a great deal. A slipping kneecap produces a yelp.

Degenerative myelopathy does not, because it destroys the conducting pathways rather than compressing or inflaming them. A dog with early DM walks with its hind feet in the wrong places but shows no reaction whatever to having the spine, hips and knees flexed, extended and pressed.

What it produces instead is proprioceptive loss: the dog no longer knows precisely where its back feet are. The signs follow from that. The tops of the hind nails wear down because the foot is dragged rather than lifted. The feet cross over one another when turning. The dog stands with a hind foot knuckled over onto its knuckles and does not correct it, which a neurologically intact dog does instantly.

Appetite, alertness and enthusiasm stay entirely normal, which many owners find the most difficult part.

The disease was first described in German Shepherds and is best documented there, in Pembroke Welsh Corgis, in Boxers, in Chesapeake Bay Retrievers and in Rhodesian Ridgebacks. Those are the populations in which the genetic variant is common and in which the clinical disease has been confirmed at post-mortem.

The Papillon's documented health list contains patellar luxation, progressive retinal atrophy, dental disease, an open fontanel and a collapsing trachea. Nothing spinal, and nothing neurological.

A further complication is that the DNA test reports genetic risk, not disease. A dog can carry two copies of the at-risk variant and never develop clinical signs, which means a positive test in a breed where the disease is not established should be interpreted cautiously rather than treated as an answer.

What this means practically is that a wobbly-legged Papillon needs a proper neurological and orthopaedic examination first. In this breed the answer is far more often a knee, a joint or, occasionally, a compressive spinal lesion that is actually treatable.

If you think your Papillon has degenerative myelopathy, 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 patellar luxation, progressive retinal atrophy, dental disease.

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 degenerative myelopathy it is often what separates a clear pattern from a guess.