Canine degenerative myelopathy (DM) is a progressively degenerative disease of the spinal cord which causes hind limb weakness, lameness and eventual paralysis. It appears to affect dogs between the ages of 8 - 12 and the prognosis for total paralysis is around 12-24 months. With this disease, the myelin sheaths that normally protect the spinal neurons disintegrate, exposing the underlying nerve fibers and disrupting the communication pathways between the brain and spinal cord. The precise cause of degenerative myelopathy is unknown.
You can use the chart below to determine the status of puppies from a breeding with each parent being either clear/carrier or affected.
Puppies will be 100% clear by parentage
50% clear / 50% carrier
CURRENT LIST OF TESTED DOGS AS PUBLISHED BY THE KC HERE
Dogs can be tested with a simple buccal cheek swab at home and sent to a Laboratory for example Laboklin.
Clear: Dog is negative for the Degenerative Myelopathy mutation.
Carrier: Dog carries one copy of the mutation associated with Degenerative Myelopathy, and could pass on the mutation to any offspring.
Affected - At Risk: Dog has a significantly higher risk of developing DM, and will always pass on a copy of the mutation to its offspring
UNIVERSITY OF MISSOURI DM HANDOUT (PDF DOCUMENT) DOWNLOAD HERE
There are several stages of the disease, and it can develop quite rapidly.
Initially you may notice rear limb weakness, muscle mass loss and dragging of one or both of the hind legs. I didn't notice any dragging of the feet initially, but did hear her nails scraping on the ground on hard surfaces. You may also notice a change in their gait, or them standing cow hocked.
DM has a slow onset and if your dog shows any sign of pain, you are not dealing exclusively with DM. Other conditions that can appear like DM require different treatment therapy and may require restricted exercise, so it is important you ask your vet to check your dog to rule out other conditions involving the spine. DM is almost unheard of in a dog under the age of 5 years of age.
If you have a presumptive diagnosis of DM from your vet you can use a harness or sling which will help your dog stand and can also be used to help when walking. You can also use boots to protect their feet. I have found the best ones, only available from the US are these from DogBooties.com, and I have a cupboard full of boots that were useless.
If your dog has DM, you should continue with exercise to maintain muscle mass. Swimming/hydrotherapy, or walking in water is very effective in maintaining muscle mass.
Not everyone will like the idea of a wheelchair, but Teisha took to hers straight away and I found it excellent to keep her mobile when she started to lose the ability to hold her weight with her back legs (see videos below). She was still part of the pack and still enjoyed running with the others and chasing a ball.
In the late and end stages of DM, the progression is quicker. It can plateaux for a while, then you will see forelimb weakness with muscle mass loss to the shoulders. Eventually your dog will be unable to stand or walk. There may be some head movement at this stage, but eventually they will not be able to remain upright on their belly without assistance. The nerrous system's spinal cord and brain stem are the only structures affected by DM, however weakness from DM can have secondary effects such as pressure sores, systemic infections and UTI due to urine retention.
A dog can pass naturally from end stage DM, but care is essential as they can eventually have kidney, lung and liver failure together with asphixiation, which can be very distressing for both the dog and the owner.
Most people who care for their dogs, even to end stage, will monitor them and choose euthanasia as soon as changes occur to ensure the very end stage is not reached.
The single nucleotide substitution in the gene called SOD1 that causes Degenerative Myelopathy is autosomal recessive with incomplete penetrance. This means that dogs that carry two copies of the mutation (homozygotes) are at increased risk of developing Degenerative Myelopathy during their lives. Dogs that carry a single copy of the mutation (also known as carriers or heterozygotes) are less likely to develop Degenerative Myelopathy as a result of the SOD1 mutation, but they will pass the mutation onto about half of any offspring they have. Breeding dogs that are less likely to develop Degenerative Myelopathy should be the breeder’s priority, with a reduction in mutation frequency within the whole breed being the secondary, longer-term target.
Carriers can be bred from safely, provided they are mated to a dog that has also been tested and is clear of the SOD1 mutation (i.e. carry no copies of the mutation). If a carrier is mated to a clear dog approximately half of the resulting puppies will also be carriers, so should be tested themselves prior to breeding. Breeding carriers to tested, clear dogs is safer, in terms of avoiding dogs affected with Degenerative Myelopathy, and will help to maintain the genetic diversity of a breed.
However the story of degenerative myelopathy is not that simple and the disease has been confirmed in some dogs with only one copy of the gene suggesting that there are other genetic or environment influences that determine whether a dog will develop the disease. One reference is –
Zeng R, Coates JR, Johnson GC, et al. Breed distribution of SOD1 alleles previously associated with canine degenerative myelopathy. Journal of veterinary internal medicine / American College of Veterinary Internal Medicine 2014;28:515-521
The University of Missouri recently found that an E40K missense mutation of superoxide dismutase-1 (SOD 1) is strongly associated with this disorder. SOD 1 is a gene that encodes an enzyme (superoxide dismutase) responsible for destroying free radicals in the body. Free radicals are reactive entities that are part of the natural defence mechanism; however they become harmful when they are produced in excessive quantities, causing cell death and a variety of degenerative diseases. The same gene mutation also can cause a form of human motor neuron disease called amyotrophic lateral sclerosis. However, the actual mechanism of the disease is still not clear.
Crisp MJ, Beckett J, Coates JR, et al. Canine degenerative myelopathy: biochemical characterization of superoxide dismutase 1 in the first naturally occurring non-human amyotrophic lateral sclerosis model. Experimental neurology 2013;248:1-9.
Awano T, Johnson GS, Wade CM, et al. Genome-wide association analysis reveals a SOD1 mutation in canine degenerative myelopathy that resembles amyotrophic lateral sclerosis. Proceedings of the National Academy of Sciences of the United States of America 2009;106:2794-2799
DNA testing for the SOD-1 gene identifies dogs that are ‘clear’ i.e. the dog that has two normal copies of the gene and is extremely unlikely to develop DM; those who are ‘carriers’ i.e. dogs who have one normal copy of the gene and one mutated copy of the gene have less chance of developing DM [but may do so,, either because of other influences or because the recessive gene is switched on]. those who are ‘at risk’ i.e. dogs who have two mutated copies of the gene and are at risk of developing DM. However, the test does not identify dogs that are affected by the disorder, but only identifies dogs that are more at risk of developing clinical signs, but may not do so during their lifetime
Ultimately, a diagnosis of degenerative myelopathy is made by ruling out other diseases that cause progressive paralysis. Samples of cerebrospinal fluid can be taken and assessed for increased protein levels. Advanced imaging procedures can be performed to rule out other conditions.
DM causes insidious and progressive lack of muscle coordination, called ataxia. The hind limbs usually are affected first by weakness and slight or incomplete paralysis (paresis). Owners will notice some or all of the following symptoms on affected dogs:
Dragging of the rear paws and knuckling-over on the rear toes
Sores on the tops of the paws
Signs of wearing on the toenails.
Odd, spastic gait
Difficulty jumping, running, rising or walking
Muscle atrophy on the dog’s hindquarters from disuse
Paralysis of the rear legs
Possible front limb paralysis
Three dog breeds have a particular heightened risk of developing or passing on the gene mutation that causes canine degenerative myelopathy, and these are the German Shepherd, Boxer dog and Pembroke Welsh Corgi. Overall, however, 43 different breedsof dog have been identified as having the propensity to develop and pass on the gene mutation, but most commonly include the Boxer, Chesapeake Bay Retriever, German Shepherd, Pembroke Welsh Corgi, Cardigan Welsh Corgi, Rhodesian Ridgeback, Poodle, Wire Fox Terrier, and Labrador Retriever. The mean age of affected dogs is 9 years. Males and females are equally affected. Younger dogs also can be affected, but this is uncommon.
Any dog can get DM. Being homozygous for the gene makes it more likely that a dog will get clinical DM, but a clear or carrier does not mean they will not get DM, clear and carrier dogs have been confirmed with DM on autopsy, DM cannot be diagnosed without an autopsy. DM is a disease that looks like other diseases, and many other diseases can look like DM. DM is a specific disorder, it is not a back problem, where a dog loses control of its back legs, limps or has progressive paralysis. It is not the only nerve disorder and it is not the only thing that makes dogs lose rear function. Dogs can “go down” because of disc disease, a whole load of muscle diseases, other nervous disorders, vestibular issues, a huge range of injuries, and even the simple muscle atrophy of old age. Any one of these can mimic DM.
Exercise and other forms of physical therapy are very important to help delay the onset of disuse muscle atrophy associated with DM and to help affected dogs maintain mobility and strength in their pelvic limbs. This commonly involves what are called “range of motion” exercises (passive stretching and flexing of the rear legs by hand in a regular pattern). Activity seems to slow the progression of the disease, and as a result with regular physical therapy affected dogs are able to maintain strength, balance and the ability to walk for a longer period of time. Recently, hydrotherapy also has proven to be beneficial for dogs with this disease. This involves swimming exercises, underwater treadmill use and other techniques that help the dog exercise and use its muscles.
A viable management option for dogs that have lost mobility in their pelvic limbs is the use of a wheel cart – essentially, a wheelchair for dogs. As long as the dog is able to use its front legs normally, a wheel cart will keep it comfortable and mobile. Once the front limbs are severely affected, a wheel cart cannot be used. Your veterinarian can help you find a wheel cart suited to your particular dog.
No drug has proven effective in slowing or stopping the progression of canine DM. Vitamins and omega-3 fatty acid supplementation have been advocated as potential therapies but are not yet proven. Vitamin E, vitamin B complex and vitamin C are under investigation as possible useful supplements for managing this disease. Their efficacy also is unknown. Other chemical therapies are being studied, including administration of aminocaproic acid and the potent antioxidant, acetylcysteine. These experimental treatments have some adverse side effects, are expensive and may require long-term use. Still, if no other treatment protocol helps a particular dog, these unproven “treatments” may be considered. Of course, a veterinarian is the only one able to assess and decide upon the right treatment regimen for an affected dog. The suspected diagnosis of degenerative myelopathy is based on clinical signs, breed, and age and supported by the absence of other clinical diseases.
A diagnosis of degenerative myelopathy is devastating and I can say that as an owner who has lived through it.
To find out that your dog has a progressive neurological condition that will eventually lead to paralysis is heartbreaking.
It is often hard to grasp the disease progression because your dog is usually doing very well when symptoms are first noticed. If you have gone through this experience, you will have lots of questions running through your head. Is it going to hurt, how long does my dog have, can I do anything to slow it down….? And the list goes on.
Daily physiotherapy can help and a 2006 study found that physiotherapy can extend a dog's life up to 255 days when DM is suspected. The study described the following components of physiotherapy being, active exercise, passive exercise, massage, hydrotherapy (deep water walking, underwater treadmill, etc), paw protection (boots on affected limbs)
A different study added nutrition and feeding unprocessed foods and supplements in addition to exercise to slow down the progession of the disease. Acupuncture is another therapy that has been effective in treating DM.
THERE IS NO CURE, BUT SOME OF THESE TREATMENTS AND SUPPLEMENTS HAVE BEEN RECOMMENDED TO ME
Weekly hydrotherapy as soon as you notice any differences in your dogs gait
either swimming or in a water treadmill, together with laser treatment, acupuncture and phsyiotherapy.
If you know a vet practice, physiotherapist, or hydrotherapy clinic that has the extra strong lasers, I believe they are around £29000 to buy, some manufacturers say they have been proven to extend the life of a dog with DM for up to 3 years.
Above all, keep your pet active, when they start to drag and/or knuckle a back leg, walk them on grass, once you stop walking them they will lose muscle. If you have slippery floors use rugs and runners so they don't slip. You can also buy non slip paw pads, which you stick onto their paws or boots/socks, waterproof boots, and these cordura boots made out of a type of backpack material HERE. The latter only available in the US at the moment, but they will ship to the UK and feedback has been that they are not only comfortable for the dog, but they stay on well.
My experience with my own bitch........
I noticed some changes to her gait August/September 2020, then she started to kick one of her back legs out so we
started hydrotherapy. Unfortunately she developed a hot spot, which took months to heal, and by the time I was able to start back in
January 2021 she was very cow hocked. Vet confirmed my fears in March 2021, a few days before her 8th birthday.
I kept her as active as possible, she loved to go out with the other dogs, but she was kept on a long lead so they didn't knock her over.
By July 2021 she was unable to go upstairs and struggled with steps although if we tell her she can do it, she will try. She was still going a walk over the fields on soft grass so she doesn't graze her paws when she drags her back leg. She could come downstairs, but I held onto her so she doesn't slip and tumble down.
Whilst I knew about DM as we have had a dog with it before, she was a lot older, and having a beautiful young bitch who, in her own head is full of life, is heartbreaking.
video below is a month after the one above
October 2021 - Whilst Tei still had the use of her back legs, and still does one lap of the field, she
was not as agile and whilst I said I would never put her in a wheelchair, it has given her back her freedom
when going over the fields with the others.
Below June 2022, my beautiful little girl, so full of life in her head, but her back legs are no longer able to take her weight
I know there are still some breeders who have not experienced DM in any of their Collies, and I for one was oblivious to how many breeds are now affected. One breeder told me that only the American Collies are health tested and clear of certain DNA tested diseases, which is totally untrue. Another asked me what she was supposed to do with DM affected puppies, and thought she was going to be expected to cull them.
I have had at least one DM affected/at risk puppy in a litter I bred and had I known what I know now, this could have been avoided by using a dog clear of the DM gene. There is nothing to say if this dog will develop the disease, but I have to live with it.
There is no reason to exclude any DM affected dogs from a breeding programme, but if you mate with a DM clear dog you will get 100% carrier puppies in the litter, which is a whole lot better than having affected puppies in a litter. The test presently costs around £50 with Animal Genetics or Laboklin (2022), and is a simple buccal cheek swab.
Recomennded walking aids
BIKO PHYSIO BRACE HERE (ensure you measure correctly as if it is too loose or too tight, it won't work effectively)
You may find a second hand set of wheels HERE and in the UK HERE
Unfortunately we had to say our last goodbye's to Tei on the 10th November, 2022, she would have
been 10 years of age in the following March, gone far too soon, run free my precious little girl
If you would like to make a donation to the Cure 4 DM foundation you can do so
via paypal using this email address - email@example.com
HEALTH TESTING RESULTS AS PUBLISHED BY THE KC
PLEASE NOTE THAT THIS IS NOT UP TO DATE AS THE KC
ONLY UPDATE TWICE A YEAR AND A LOT OF BREEDERS
CHOOSE NOT TO PUBLISH THEIR RESULTS PUBLICLY
I have undertaken a lot of work on the Pedigree database and added all known Health Test results
to each dog HERE
Veterinary Centers of America
American College of Veterinary Surgeons
Washington State University
American College of Veterinary Surgeons
Dogs Naturally Dr Conor Brady
This information is not meant to be a substitute for veterinary care. Always follow the advice provided by your veterinarian.