Degenerative myelopathy or arthritis? How to tell the difference

Your dog's hindquarters are going downhill. One vet says arthritis, online you read about degenerative myelopathy and in the early stage those two look strikingly alike. The difference is huge, though. Arthritis hurts and can be treated. Degenerative myelopathy does not hurt and cannot. What you do at home, what to expect from the coming months and which aids are worth buying: it all hangs on that one question.

Below are the signals that separate the two, how a vet reaches a diagnosis and what does and does not work.

What degenerative myelopathy is

Degenerative myelopathy, usually shortened to DM, is a disease of the spinal cord. The nerve pathways that carry the signal from the brain to the hind legs slowly break down. The message stops arriving. In the early stage there is nothing wrong with the muscles themselves, only with the steering.

The comparison vets often make is with ALS in humans. In broad terms that fits: it is progressive, it starts at the bottom and there is no treatment that stops it.

There is a hereditary side. A mutation in the SOD1 gene is present in almost every dog with DM. The breed you see most often is the German Shepherd, but the Pembroke Welsh Corgi, the Boxer, the Rhodesian Ridgeback, the Chesapeake Bay Retriever and the Bernese Mountain Dog are in the risk group too. The first symptoms usually appear after the age of eight.

The most important feature for you as an owner fits in one line: DM is painless. A dog with DM loses the use of its hindquarters without feeling any of it.

Arthritis and DM side by side

This table is what the article is built around. Work through it with your own dog in mind.

Two rows in that table weigh more than the rest: pain and direction. A dog that gets up stiffly and walks normally ten minutes later has a joint problem. A dog that slips a little further every week without ever having a good day probably does not.

The four signals that tell you most

1. The paw lands the wrong way up

This is called knuckling. Your dog puts a hind paw down with the toes curled under, so it stands on the top of the paw instead of the pad. It does not correct that, because it cannot feel the paw is wrong.

You can trigger it yourself. With your dog standing, gently turn one hind paw over so the top touches the floor. A healthy dog puts it back within a second. A dog with DM leaves it there. That is not proof, but it is a strong signal to take to your vet.

2. The tops of the nails wear down

Because the paw drags across the floor instead of lifting, the nail scuffs on the wrong side. Look at the hind nails and compare them with the front ones. If you see a slanted, worn top edge or a bald patch on the upper side of a toe, that paw is dragging. With arthritis that does not happen.

3. The walk is drunk, not stiff

Arthritis makes the gait short and careful. DM makes it wobbly. The hindquarters sway, the legs sometimes cross and on a turn the back end swings through. A dog in pain moves in a controlled way and holds itself back. A dog with DM moves without control while holding nothing back.

4. Painkillers do nothing

This is the sharpest distinction available to you in practice. If your vet prescribes an anti-inflammatory and after a week you see no difference at all in how your dog stands up and walks, the arthritis diagnosis is probably wrong. Or at least incomplete. Raise it, because that is exactly the sort of information a vet can use.

Not sure whether your dog is in pain at all? Dogs barely let it show. In recognising pain in your dog the quiet signals are lined up. The early signs of joint wear are in recognising arthritis in dogs.

How a vet reaches the diagnosis

Be prepared for this: DM is a diagnosis of exclusion. There is no test that tells you "this is it" in a living dog. Your vet first rules out everything that looks like it and can be treated.

• Neurological examination. Reflexes, postural reactions and the knuckling test. This tells you whether the problem sits in the nerves or in the joint.
• Imaging. An MRI or CT to rule out a herniated disc, a tumour or a narrowing of the spinal canal. This is the key step, because a herniated disc looks like DM and can sometimes be operated on.
• DNA test. It looks for the SOD1 mutation. Watch the trap here: a great many dogs carry that mutation without ever getting ill. A positive test therefore does not confirm DM, while a negative one does make it a good deal less likely.

Certainty only comes after death, through examination of the spinal cord. In practice a vet works with a strong suspicion based on the picture, the age, the breed and what has been ruled out.

What actually helps your dog

There is no medicine that stops or slows DM. That is the unpleasant truth. There is one thing with real evidence behind it: movement.

Research in dogs with DM shows that animals given intensive physiotherapy stayed mobile longer than animals that were not. That means controlled exercises, treadmill work and often hydrotherapy, where the water carries the weight while the muscles keep working. What such a programme involves and costs is in dog physiotherapy.

Beyond that, this helps:

• Weight. Every kilo less is a kilo a weakened hind end does not have to carry.
• Keep walking, shorter and more often. Three calm twenty-minute walks beat one long one that leaves him exhausted.
• A support sling or harness with a handle. You take over part of the weight while your dog keeps stepping. That last part is the whole point: stepping keeps muscle mass on.
• A dog wheelchair. Further along, a cart gives many dogs their walk back. They usually adjust faster than their owners expect.
• Sorting out the floor. A dog that cannot feel where its paws are should not have to deal with a slippery floor on top of that.

What socks do here and where they stop

We sell grip, so let us be clear about what that is worth in this case. DM is not a grip problem. It is a steering problem. A sock changes nothing about the disease and does not slow it down.

Where they do help early on: as long as your dog still has strength and is mainly unsteady, grip on laminate or tiles takes the sliding out. That saves startled moments and it spares the muscle he still has. Our anti-slip dog socks have silicone grip on the top and the bottom, so even if the sock turns a quarter there is still grip under the paw. You set the size by the width of the spread paw print via the size calculator.

Where they stop: once your dog really starts knuckling, he drags across the top of the paw. A sock protects that skin for a while, but it also wears through there fast. That is not a construction fault, that is a sock being used for something it was never built for. At that stage, ask your vet or physiotherapist about protectors made specifically for dragging paws, with a reinforced upper.

And once the hindquarters genuinely give out, no sock is the answer. Then you are talking about a support sling, a cart and your vet's guidance.

When it is not DM and you should call today

DM creeps in. If things go wrong within hours or over a single day, something else is happening and every hour counts:

• The hind legs fail completely and suddenly.
• Your dog screams or yelps when moving or when you touch the back.
• He loses control of urination or defecation from one moment to the next.
• He feels nothing when you pinch a toe.

This fits a herniated disc or a blood clot in the spinal cord. Both are time-critical and in both, acting fast is what makes the difference. More on sudden versus gradual weakness is in dog's hind legs giving out.

In short

Pain and direction are your two best measuring sticks. If it hurts and there are good days and bad days, you look at the joints. If it does not hurt, a paw drags and it moves a little further every month, then the question about DM belongs on the table at your vet. Have a herniated disc ruled out before you settle for the diagnosis, because that is the one possibility something can still be done about.

Is your dog still walking and sliding around the house? Then start with the size check and you will know the right size within 30 seconds.

Frequently asked questions

Is degenerative myelopathy painful for a dog?

No, DM itself is painless. That is immediately the clearest difference from arthritis. A dog with DM can of course have arthritis alongside it. In that case there is pain. If your vet finds both, the pain gets treated while the DM is managed.

How fast does degenerative myelopathy progress?

The pace differs per dog. Most owners see a clear deterioration of the hindquarters within six months to a year. After that it spreads further forward. The whole course often takes one to three years. Physiotherapy can stretch that time. It does not stop anything.

Can a DNA test tell me whether my dog will get DM?

The test shows whether your dog carries the SOD1 mutation, not whether it will fall ill. Many carriers never develop symptoms. The test is useful for breeders and as support for a diagnosis, but it is not a prediction. Once there are symptoms, neurological examination plus imaging remains the route.