Degenerative Myelopathy In Dogs

Updated April 13, 2021

How can I talk about one of the most hopeless diseases of dogs without sounding hopeless? Like this:

Many cases of degenerative myelopathy are probably misdiagnosed

It starts with Google. Put in either weak back legs or dragging back legs and you might only get the wikipedia page on degenerative myelopathy (DM).

You will see in a minute how wrong this is. Of course, vets don’t use Google, but they face their own major hurdles in getting an accurate diagnosis, as you’ll also see.

What Is Degenerative Myelopathy?

DM is a disease causing slowly progressive loss of neural tissue in the spinal cord. It starts with weakness or wobbliness (paresis or ataxia) in the back legs, eventually leading to complete paralysis. At this point the dog drags the back legs and cannot stand up on their own.

Further progression causes the same to occur in the forelimbs, plus urinary and faecal incontinence, and still further to respiratory failure. DM is now believed to be very similar to the human disease amyotrophic lateral sclerosis (ALS) or motor neurone disease.

The age of onset is late, with an average of 9 in large breed dogs and 11 in Pembroke Welsh Corgis. Large breed dogs diagnosed with DM go from mild signs to being unable to walk in 6 to 9 months. The same figure for smaller breeds might be slightly over 12 months.

Breeds Affected With DM

Degenerative myelopathy is now known to be a genetic disease. It was first described in the German Shepherd, and this remains the key dog breed we see with it. However, it can occur in almost any breed of dog, and especially these:

  • Bernese Mountain Dog
  • German Shepherd Dog
  • Pembroke Welsh Corgi
  • Finnish Lapphund
  • Soft Coated Wheaten Terrier
  • Cavalier King Charles Spaniel
  • Rhodesian Ridgeback
  • Boxer

Dogs usually only show the signs of DM after already breeding and passing it on. Therefore, although I am very critical of some breeding decisions, DM was nearly impossible to eradicate until the development of genetic testing.

Diagnosis Of Degenerative Myelopathy

dog knuckling paw

Traditional diagnosis of DM has relied on identifying the signs in a dog of the right breed and age.

All affected dogs show at least some knuckling of the hind limbs (pictured here in a Cavalier King Charles). This is demonstrated by turning over the paw while supporting the body. An affected dog is unaware of the position of their paw and so does not return it, or does so slowly.

They will also often stumble and drag the hind legs. All these signs are typical of any spinal disease, such as:

It is often said that DM can be identified by a lack of pain, but this is very misleading. DM may be painless, but most dogs with severe chronic pain will display no signs. Therefore, I have also seen cases of severe hip dysplasia, cruciate ligament rupture or arthritis get mistaken for DM.

Degenerative myelopathy is described as a diagnosis by exclusion. The only way to prove it is to rule out all the other possibilities, which almost inevitably requires advanced imaging such as MRI. Sadly, this is unrealistic for most dog owners.

Does Misdiagnosis Matter?

My best clue that a dog doesn’t have degenerative myelopathy is when the disease progresses more slowly than expected. Getting the diagnosis wrong only matters if the other disease was treatable. This is certainly true for any painful condition.

Therefore, all dogs with suspected (but not confirmed) DM should at least go on a trial of pain medication. Even if they truly have DM, their signs may be caused by a mix of conditions including arthritis, and so some improvement is common.

The other neurological conditions are much harder to treat, but have possible positive outcomes with specialist surgery. The problem most dog owners face is that the investment in reaching the diagnosis is considerable, for such an uncertain outcome. That’s why, although I will offer referral as a best case, I won’t expect everyone to take it.

In 2020, here’s what I now recommend…

Genetic Testing For Degenerative Myelopathy

The genetic fault for most cases of DM is now well-understood and a commercial test is widely available around the world. Owners can even do it themselves. Here in Australia an SOD-1 swab costs under $100.

A positive test does not guarantee that a dog will be affected, but it’s a great tool for choosing which dogs to breed. That’s why I have hope for the future.

For dog owners facing the decision on whether to see a specialist it’s also potentially a great help. If a dog has a positive test, it makes the diagnosis of DM all the more likely. If on the other hand, the test is negative, or a dog has improved on a medication trial, then just maybe the disease is actually something that could be managed better if we knew what it was.

Treatment Of Degenerative Myelopathy

Even if your dog has DM, the outlook isn’t hopeless as long as you’re careful and know when to stop. They aren’t in pain so your big focus should be on maintaining quality of life.

I cannot stress this too many times: there is no treatment available for degenerative myelopathy. Not prednisolone or other corticosteroids, not vitamin E, not CBD oil. If you get a response to treatment, you should re-evaluate the diagnosis.

In the early phase of DM, much improvement in walking can be had just by adding more grip to slippery floors by the use of carpet runners etc. Then, as the back feet start to scuff on the ground, you need to prevent open sores from forming. There are plenty of people selling dog booties, or your vet can show you how to use products like ‘Vet Wrap’.

Negotiating stairs gets challenging so baby gates are a good idea. Special harnesses with back handles (such as the Rogz Explore®) are even available to help them go up and down or into cars. Physiotherapy and hydrotherapy have been shown to slightly prolong life.

As for the use of carts, my advice is to remember three important things:

  1. DM progresses quickly
  2. The front legs are affected not long after the back legs
  3. What you see on social media may not be the whole story

If you get a cart, you probably only have a short time before the front legs aren’t strong enough any more. I also worry a lot that the dogs aren’t always comfortable, so I ask owners to be very realistic and self-critical in using them.

Talking about euthanasia is a terrible place to finish, but it doesn’t have to be feared. Most dog owners who reach this point do so with their dogs retaining dignity and quality of life. They know they’re doing the right thing, and the actual event is much, much better than they ever expected or feared.

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By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These articles are from a series regularly posted on email and Twitter. Subscribe via email here to never miss a story!

Andrew

3 Replies to “Degenerative Myelopathy In Dogs”

  1. I dont know if you can advise on this, but my 15 year old beagle mix has something we thought was DM. It started in 2018 with some wobbly back end when walking. She now has a hard time walking on our hard floors and back legs give out and she cant stand up. Then after a few minutes she gets up and walks but not normal. Her thigh muscles are wasting she favors her left rear leg and licks it all the time. But both back legs are weak, my vet thought DM at first, but now isnt sure. When i massage her back by her tail she stretches her back legs out and i can push against her feet and there is resistance, like she is pushing back, does DM let them have strength to push back?
    We are going to try treatment for arthritis again, but she never cries in pain, and if you rub her back and hips she seems to like it. So they say DM isnt painful, and she dont seem to be in any pain. But her back end is really weak, she can still climb up stairs and on the sofa she pushes up with her better right rear leg. Its 2021 and my vet thought by now she would be paralyzed, so now he is rethinking DM, but he isnt sure. I dont know what to do, he checked her spine for disc problems just normal old dog discomfort no slipped disc. But her back legs are wasting and weak, but she still walks and even trots after my other dog. Of course her back legs go out sometimes when out in the yard with the other dog, and on the hard floors. I guess what im asking is would she have remained mobile for so long with DM?

    1. Hi Dana. It seems very unlikely to be DM, and the best thing you can do is investigate a little further. X-rays would seem most sensible as a first step. Otherwise we are just guessing. And as I say in the article, dogs rarely cry in pain regardless of the cause.

  2. The most helpful explanation of DM I have found. We think our 12 yo Rhodesian may have DM. She will see the veterinarian next week to rule out other obvious causes of her hind leg weakness.

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