CDRM, which stands for chronic degenerative radiculomyelopathy, is a disease most commonly seen in German shepherd dogs. An alternative name for the disease and less of a mouthful is degenerative mylopathy. CDRM is an autoimmune disease, similar to muscular sclerosis in humans. This means that the dog's immune system attacks their own nervous system.
CDRM can strike dogs as young as five years old. Over the course of six months to two years the dog's gait deteriorates with the hind legs becoming uncoordinated, swaying or crossing over. Ultimately the dog will be unable to walk without assistance. Once the disease becomes incapacitating the dog will often be euthanised as it is difficult to maintain a good quality of life for them. When you bear in mind that an adult GSD can weigh 70lbs (5 stone) or more you can appreciate that there is often a physical difficulty for the owner attempting to help such a large dog to walk.
The only good thing about CDRM is that it doesn't seem to be a painful disease,
Which Breeds are Affected by CDRM?
German shepherd dogs are the breed mainly associated with this disease and it affects German shepherd crosses too. Other breeds can certainly be affected by a spinal cord disease. Research into the canine genome at the University of Missouri has shown up a gene mutation in 115 breeds including boxers, Pembroke corgi, Rhodesian ridgeback and Cheasapeake bay retrievers as well as the GSD which seems to be a cause of CDRM. (Clare Rusbridge BVMS Oct 2012). It is possible to test your dog’s DNA to see whether the gene is present. The gene doesn't guarantee the dog will develop CDRM, but is a predisposing factor. The fact remains however that it is German shepherd dogs who comprise the majority of clinical cases of CDRM. Studies have found 56-82% of CDRM cases are GSDs and as many as 1 in 5 German shepherds may develop it.(Fred Lanting 2012)
Breeds other than the GSD which seem to have a slightly greater risk of developing CDRM are Belgium shepherd, old English sheep dog, Rhodesian ridgeback and weimaraner (R.M. Clemmons)
CDRM usually begins in dogs aged 8 – 14, but there are instances of it occurring earlier or later. For example, Nettle, my German shepherd cross is 16½. He only began showing possible signs of CDRM 18 months ago with an occasional slight dragging of one hind leg. At that point those signs seemed connected with his arthritis and spinal column degeneration.
It often isn’t easy diagnosing CDRM especially in older dogs who may be arthritic and already showing an altered gait because of this. The earliest sign is often the inner nails of the back paws showing extra wear or noticing intermittent slight dragging in one or both of the hind legs.
You might hear this happening if your dog is walking on a paved area or you might just notice the back foot is briefly curled and dragging as the dog moves that leg forward. As this happens more frequently the nails on the hind feet become noticeably worn down.
The vet may test your dog’s proprioception (sense of position) by putting a hind foot in a knuckled over position. If your dog is slow to reposition its foot or unable to do so this is an indicator of CDRM.
As the disease progresses the back legs become weaker and this can include reduced tail movement or a limp looking tail. Bowel and urinary incontinence is quite likely to occur later on.
At the moment a definitive diagnosis can only be given via a post mortem which checks for damage to the myelin sheath around the nerves in the spinal cord. However work is being done to identify changes in the dog’s blood profile which may lead to the development of a blood test for the disease.
Degenerative Myelopathy Treatment
Sadly there isn’t a cure for CDRM and it is a degenerative disease meaning that the symptoms get progressively worse. However there is some evidence that a holistic treatment approach can slow down progression of the disease.
Regular exercise, especially walking or swimming, will help build up the dog’s muscle strength and tone and possibly help keep the nerves firing for longer. It will also help maintain your dog’s interest in life. If the dog has not been exercising much or you decide to introduce an exercise like swimming for the first time it is vital to build up exercise very gently. It can be good to let the dog alternate rest day with exercise days to start with.
A dog 'Kart' or 'Wheelchair'
This can help a dog with CDRM to remain mobile
A Dog Body Harness
A harness enables the owner to bear some of the weight of their dog and help prevent the dog falling over.
If the dog’s ability to walk is severely limited due to weakness or falling over a lot it you can try body harnesses which enable the owner to give the dog some extra support or a kart which entirely takes over for the back legs. The kart is a useful option if the front legs are strong and sound, because it can take the physical strain off the owner, but it isn’t something that all dogs take to.
Nettle up until the last six weeks has been walking for an hour or more 3 or 4 days per week. He also had 10 sessions of hydrotherapy 12 months ago. His ability to manage exercise is diminishing now though. Thirty minutes is now his maximum daily amount.
Some people advocate a natural food diet ideally home made for a dog with CDRM. There are many supplements which may help and which even have the backing of ‘good science’ as to why they may help. Unfortunately clinical trials showing conclusive proof for the supplements are thin on the ground. Suggested beneficial supplements include vitamin B, glusoamine, curcurmin (found in turmeric) and omega 3. Please consult with a vet before starting any program of food supplements for your dog.
Nettle has an ordinary locally milled dog kibble diet, but has been receiving a high quality glucosamine supplement for the past 5 years to support his arthritis which may have had some positive effect on the progression of the CDRM too.
Dr Clemmons a vet with the University of Florida, USA is one key person researching into treatments for CDRM (degenerative myelopathy). He states that there are two medicines which either halt progression or result in remission of the disease in 80% of the patients that he sees. These are aminicaproic acid and n-acetylcysteine. You will need to get these drugs by prescription and I understand this is more easily done in the USA than the UK. If your own vet is unfamiliar with Dr Clemmon’s work, it may help to direct them to it.
Veterinary researchers at the University of Missouri appear to be unconvinced by this and state that there is no scientific evidence that any of the cures currently offered for CDRM work. (Missouri Canine genetic diseases)
It is hard for the dog owner to gauge the right course of action, some owners are keen to leave no stone unturned and try everything which is inevitably very expensive, others take a more restrained approach in the absence of conclusive evidence.
There is an indication that stress such as undergoing an operation or hospitalisation, can hasten the progress of the disease. Dr Clemmens feels this can be mitigated against to an extent by ensuring that a hospitalised dog continues to exercise.