Degenerative myelopathy (DM) is generally associated with a genetic abnormality in dogs. It is a slow-onset, non-painful destructions of the nerves in the spinal cord, which are associated with conduction. In degenerative myelopathy, both the thoracic (upper and middle back) and lumbar (lower back) parts of the spinal cord are affected.
As the disease progresses, a dog will gradually develop weakness and an abnormal gait in their hind limbs. Usually, it is not completely symmetrical, so your dog will struggle with more weakness on one side of their body than the other. As degenerative myelopathy advances it causes progressive paralysis of the hind limbs. Very sadly the entire spinal cord will eventually become affected—causing forelimb paralysis and problems with breathing, continence and eating.
Prognosis is poor, typically around one year after onset of the first symptoms, a dog is unable to walk on their hind limbs.
Signs and symptoms of Degenerative Myelopathy
A dog suffering from degenerative myelopathy will initially be weak in their hind limbs, this can lead them to have difficulty getting up from sitting or from their bed, for example. As it progresses your dog will start to lose feeling in their hind limbs, which can cause your dog to drag their paws, they may knuckle over at the paws or have abnormal gait or paw placement. As a result of this, you may notice that your dog has scuffed toenails and/or the tops of their paws. Similarly, when walking you may notice your dog stumbling or crossing their hind legs where previously they did not.
As degenerative myelopathy progresses further, a dog will become ever more limited in the use of their hind quarters. This means that their hind legs may shake when standing due to weakness. They will not longer be able to perform tasks which they previously used to, such as jumping into the back of your car or climbing the stairs etc. Muscle wasting is often observed at this stage, sometimes this is asymmetrical but generally after a while becomes symmetrical. Inevitably incontinence issues arise, as they lose control of their bladder and bowels.
Very sadly, the paralysis which effects the hind quarters progresses to include the forelimbs and brainstem. This leads to full paralysis and the development of problems with essential daily functions such as breathing, eating and drinking.