Degenerative Myelopathy (Degeneration of the Spinal Cord)
Degenerative Myelopathy (DM) is an inherited defect where the immune system attacks the dog's central nervous system. This attack leads to a loss of insulation around the nerve fibers (myelin) and of nerve fibers (axons). Once the nerves in the spinal cord are destroyed, the dog can no longer walk because, without nerve connections, muscles cannot work. The control pathways that make muscles work are located all throughout the spinal cord.
DM is an insidious defect, the symptoms of which rarely show up before the age of 5, and possibly as late as age 14 years. The early stages of DM start with an almost imperceptible weakness in the hindquarters (also see 13, Hind Leg Weakness). In the last stage, the dog can no longer walk, nor hold balance when standing or squatting to defecate.
However, DM itself is not painful. There is zero pain because the nerve cells have died. The dog no longer feels the legs. A very stressful thought and physical experience, but without pain.
Who Gets Degenerative Myelopathy
German Shepherds are the breed that is most susceptible to Degenerative Myelopathy: Between 1 to 3% of German Shepherds worldwide are affected. However, in the USA alone, each year between 14,000 to 42,000 GSDs are diagnosed with DM - which effectively means that in the USA the proportion of affected GSDs is much higher. Simplified calculation: average 28,000 per year * average 12 years lifespan / 3.5 mio GSDs = 9.6%!
Since DM is hereditary, this means that GSD breeders have not yet taken enough care to avoid breeding affected parents. This reinforces the importance of finding the best German Shepherd breeders when you select your next GSD.
However, as with most inherited defects, both the outbreak of DM and its progression seem to be triggered by environmental intoxication. This means that you can indeed delay the outbreak of DM and slow down or even stop progression if you provide the right living environment for your dog.
Recently, the cause of DM, a homozygous SOD1 A genetic abnormality has been identified. It is recessive, which means both parents, the dam and the sire, must carry the defective gene for the puppies to develop DM later in their lives.
A simple saliva-based genetic test was developed which can help determine the risk that a certain dog may suffer DM later in life. The test costs only 65 USD.
This test is of course more relevant to those GSD breeders who aim to try their best to use breeding dogs without hereditary defects, however you too may wish to know whether your dog carries the defective A/A gene combination. In that case note that even a dog that carries the defective gene combination will not necessarily develop the symptoms of DM before the dog dies, because this depends on environmental triggers and on how early the dog dies.
During early stage DM, occasionally you can hear the sound of your dog's hind leg toe nails scraping over the pavement during walking. Your dog will begin to show some difficulty getting up. If the dog is standing, (s)he may have difficulty balancing, yet the dog can recover on his own. If you turn your dog's toes under, (s)he may still be able to right the foot pad-down, but response time may be lengthened.
As DM progresses, difficulty getting up and rear feet nail scraping will increase. The rear legs will cross under your dog's body since (s)he is losing sensation in the hindquarters: The dog does not know where (s)he has placed the feet. Faulty perception of foot placement leads to tripping and stumbling.
When your dog is in a standing position, if you move the dog from side to side using your hands, the dog will lose balance and topple over. Often, you will notice exaggerated movements, such as high stepping when going up a curb. If you now turn your dog's toes under, your dog will no longer place the foot in the proper pad-down position once (s)he can no longer feel the feet.
Soon, the tail will rarely become active and wag, however because of the length of the German Shepherd tail it may become tangled with the hind legs.
Ultimately, you will need to help a DM-suffering dog to walk at all. Up until the terminal phase, DM can take several years but ultimately the sense of feeling is completely lost, and the dog then loses control over bowel and bladder too.
Treating Degenerative Myelopathy
Although there is still no cure for DM or medication that would replace lost myelin and repair damaged axons, recent research has brought quite dramatic improvements to the life expectancy and quality of life of dogs with DM. All these improvements are centered around the goal to provide the dog with a living environment that will delay the outbreak and/or progression of DM, so that the dog dies naturally or because of some other sickness.
Treatment of a dog with the defective gene combination should ideally start before the first symptoms become visible - that's why I said above that you too may want to know whether your non-breeding dog carries the defective gene combination. In this case, in fact we are talking about avoidance measures - which may be successful to differing degrees.
Today's recommended treatment of DM combines four components:
- Other supportive measures
The more varied the exercise is that you provide to your dog, the more you stimulate the various brain functions, nerve fibres and muscles throughout the entire body. Research shows that exercise and diet have the biggest impact when we try to delay the outbreak of DM. The exercise program should comprise weekly swimming and extensive walks but should give your dog a resting day between days of heavy workout to allow strained muscles and tendons to heal and to increase the buildup of muscle strength.
In case you didn't provide your dog with much exercise in the past, you should slowly increase the schedule of alternative day exercise over the period of a month until your dog is fit. Also, if your dog is already affected by DM, you may need to help your dog to get out of the water when (s)he can no longer negotiate the bank on her own.
Important is varied exercise. Should your dog then at some point suffer DM, (s)he is optimally prepared to substitute various body functions with others that are not yet affected.
We now know that the right diet has a major impact on the outbreak and progression of DM. To give a dog the right diet is a key part of controlling environmental intoxication - which seems to trigger DM, and likely many other hereditary defects too.
This is another reason why we are against industrial dog "food", and why we stress so much the importance of healthy dog meals, regular meal times, and a consistent feeding routine on MYGERMANSHEPHERD.ORG. In particular German Shepherds with their sensitive digestion need the right diet in order to be healthy and happy. Only a healthy and happy dog can behave in a way that makes you happy too.
We cannot go into details here what the right diet for the German Shepherd and other dogs is, but the MYGERMANSHEPHERD PERIODICAL regularly features this topic too.
Recently, two medications have been identified that seem to prevent progression or even result in remission of DM in up to 80% of affected dogs: These medications are aminocaproic acid (EACA) and n-acetylcysteine (NAC). For both substances exist cheap generic products, and they can also be compounded in a local pharmacy.
Other supportive measures
Since DM is an inherited defect that causes the immune system to attack the nervous system, you must - whenever sensible in your region - avoid vaccinations, heartworm medication, and flea and tick medication, all of which increase immune responsiveness.
Stress reduction: For example, even minor invasive surgical procedures showed a marked increase in the progression of DM. Dental work can be most problematic for your dog. Aim to avoid all that causes stress.
Physical aids: If your dog is already severely affected by DM such that the dog can no longer use the hind legs properly, then the Lift Rear Harness can help your dog to walk for as long as (s)he shows walking motion - if you feel strong enough for this. The Lift Rear Harness probably is more suitable than the Support Sling:
- You keep the walking motion alive/active - this trains the dog's leg muscles and gives psychological support ("hey, I can still walk")
- You have less weight to carry!
However, if you can't get the progression of DM under control (see above how) then at a later stage there may be no way around getting the fully adjustable dog walkin wheels when the dog's hind legs show no more walking motion because the nerve fibers are destroyed.
Sorry that this topic doesn't end on a happier note, but DM in dogs really isn't a happy topic at all. That's why it is so important that GSD owners - and more so GSD breeders(!) - take all preventative action they can (see above), and otherwise treat Degenerative Myelopathy as early as possible. Thank you all.