Degenerative Myelopathy is a condition known as an auto immune disease where the immune system attacks the body’s own tissues, in this case being the central nervous system. This immune attack leads to scattered degeneration (demylination) of the myelin sheath (insulation) and axons (nerve fibres). The areas affected tend to be restricted to the thoracolumbar (middle back) spinal cord. DM affects other areas of the central nervous system, the brain stem (a stalk of nerve tissue that forms the lowest part of the brain and links with the spinal cord) and sub-cortial white matter. Both grey and white matter undergo degeneration. The reason why this disorder develops is unclear but there are probably genetic, environmental and toxic factors which may all contribute to its development. A hereditary basis for this disease is suspected, although the study of the various factors is obviously complicated. Vaccines may not help, they are over used and it is considered that they may stimulate auto immune problems.
The disease is sometimes referred to as CDRM (Chronic Degenerative RadiculoMylopathy), German Shepherd dog Myelopathy, progressive Myelopathy or most commonly DM..
The problem known as Cauda Equina Syndrome Lumbosacral has very similar symptoms to CDRM. This problem is known in German Shepherds and although it is probably congenital, signs may only start late in life. Myelography may be able to rule out DM.
Degenerative Myelopathy is seen most commonly, though not exclusively in the GSD. Affected dogs are usually over 8 years of age, but it can show over the age range from 5 – 14 years. DM is characterized by increasing loss of mobility in the hind region. Although the disease is progressive, there may be periods of apparent stability were the dog seems to stop getting worse but these are rarely permanent. Both sexes are affected.
Degenerative Myelopathy is the most common cause of progressive hind limb dysfunction in older GSD’s. Affected animals show a slowly progressive (over several months) hind limb incoordination and clumsiness and partial paralysis and weakness, with an increasing loss of mobility in the hind region. An early sign is knuckling of the hind paws especially when turning corners and dragging of the claws is also a frequent sign. Many cases are either one sided or one side tending to be worse than the other. Even in good nutritional condition, dogs show signs of increasing lack of muscle of the rear limbs. Pain sensations remain intact and incontinence is not a feature that leads to diagnosis. Diagnosis is based on the clinical findings and the elimination of evidence of any space occupying lesions by myelography.
Many people are using carts to give their dog back its freedom as best as possible, most dogs do seem to take readily to carts, but of course this is not a cure and the road which an individual owner decides to take is very much a personal matter.
It is sad that in a disease that seems to be becoming so much more common, there seems to be little information about it in text books. Although research is being carried out around the world there seems to be little information forthcoming, with the exception of The University of Florida (Dr Clemmons).
DM has been compared to the human demylination disease Multiple Sclerosis. Like MS there are varying environmental incidences with the disease being commoner in some areas.
Conventional medicine has little to offer patients with DM. On the other hand, use of exercise, certain vitamins and selected drugs have delayed or prevented progression of Degenerative Myelopathy in many afflicted dogs.
The general prognosis for this disease is very poor, most affected dogs lose all power in the hind limbs and become incontinent. Since there is no loss of brain activity until a very advanced stage the disease is particularly tragic to observe.