Degenerative Myelopathy in Dogs - Causes, Symptoms and Treatment

As its name suggests, degenerative myelopathy in dogs is a degenerative disease that affects the spinal cord of canines. It was initially known as ‘German Shepherd degenerative myelopathy’ as this was the first breed in which the condition was described. It continues to be a relatively common disease for the German Shepherd breed.

We now know canine degenerative myelopathy can affect other dogs, including mixed-breed dogs. Other breeds which are particularly susceptible include:

• Bernese Mountain Dog
• Rhodesian ridgeback
• Boxer
• Siberian Husky

It is a chronic disease with a slow and progressive action. For this reason, it affects senior and elderly dogs. It causes a slow deterioration in the functionality of the hind limbs, which finally leads to complete paralysis.

Learn more about degeneration of hind limb function in our article on why my dog is losing control of their back legs.

Canine degenerative myelopathy has a slow and progressive action. It initially registers as a thoracolumbar problem (of the spinal cord segment T3-L3) in which the following can be detected:

• Ataxia or incoordination: crossing of the hind limbs when walking, wobbling of the hip and problems judging distances may occur. Learn more with our guide to ataxia in dogs.
• Paresis (weakness of the hind limbs): difficulty walking up or down stairs is common.
• Loss of proprioception: proprioception is the body's ability to sense movement and location. When this occurs, dogs drag the toes on their hind limbs, causing wear and bleeding to the knuckles.
• Muscle atrophy: loss of muscle mass in the hind limbs.

The signs are often asymmetric, i.e. they do not appear with the same pattern or the same intensity in the two hind limbs. Over time, the neurodegenerative problem progresses to paraplegia, a complete paralysis of the hind limbs. If it continues to progress, tetraplegia could occur, something which happens with paralysis of the forelimbs and hindlimbs together.

Since its discovery, multiple studies have tried to discern the etiology of canine degenerative myelopathy. These investigations tried to associate the disease with possible nutritional deficiencies, toxins, autoimmune defects, etc. At present, the specific causes of this pathology remain unclear.

The most recent studies have identified the mutation of the SOD1 gene. This gene codes for the enzyme superoxide dismutase, as a possible cause. The high incidence of degenerative myelopathy in specific breeds suggests there is a genetic basis for the disease, so the finding of this mutation may lead to the discovery of the genetic component of this pathology.

It should be noted that the mutation in the SOD1 gene is also present in people with amyotrophic lateral sclerosis (ALS). This has led to degenerative myelopathy being used as an animal model to study this human disease.

The diagnosis of canine degenerative myelopathy is complicated. The diagnostic tests usually required for spinal cord pathologies (x-ray, magnetic resonance imaging (MRI) and cerebrospinal fluid analysis) are not useful for detecting this disease.

For this reason, diagnosis of canine degenerative myelopathy usually required:

• Neurological examination: depending on the degree of spinal cord degeneration, upper motor neuron signs or lower motor neuron signs may be detected. It is characteristic that there is no pain on palpation of the spine.
• Genetic test: a genetic test capable of detecting the SOD1 gene mutation is currently available. However, until the true etiology of the disease is confirmed, this test should only be indicative.

In summary, when the dog has symptoms of the disease, other spinal pathologies have been ruled out and they present the SOD1 gene mutation, a presumptive diagnosis of degenerative myelopathy can be made. A definitive diagnosis of canine degenerative myelopathy cannot be reached with the live animal. This is because its confirmation requires a histopathological analysis after the death of the animal.

Unfortunately, there is currently no specific or curative treatment for degenerative myelopathy. Currently, clinical trials are being carried out using inhibitors that prevent the accumulation of the SOD1 gene mutation. Hopefully, the outcome of these trials will be a commercial therapy to combat degenerative myelopathy available in the near future.

Until better therapies can be established, the the only treatment available is symptom management. One of the few effective treatments which can lengthen the dog's life expectancy is canine physical therapy. Rehabilitation programs can use mobilization exercises, stretching, massages and muscle electrostimulation to improve function and well-being. Although this therapy does not prevent spinal cord degeneration, it does aid in:

• Controlling the pain caused by tension or poor posture that the animal acquires as a result of degenerative myelopathy.
• Stopping the appearance of muscle atrophy (loss of muscle mass).
• Stimulating sensitivity of the muscles.
• Maintaining coordination and balance.

In addition, it is important to take a series of measures to guarantee an acceptable quality of life in these dogs:

• Comfort: a soft place to lie down is important to prevent pressure ulcers, but it also needs to be firm so they can sit up easily.
• Socks for dogs: to avoid the appearance of ulcers, in case they drag their paws when walking.
• Harnesses: the uses of a harness may be necessary to elevate the hind limbs or even using specific wheelchairs for dogs. The latter may be used in cases of more advanced stages of the disease.

The prognosis of canine degenerative myelopathy is serious. This is because it is a degenerative disease that has no cure. Its progress is relatively fast, meaning a dog can become paraplegic in a period of between 6-12 months.

Unfortunately, this means most dogs with degenerative myelopathy have to be euthanized for the sake of animal welfare. If not, the degenerative process can affect the brainstem, causing neurological disorders and resulting in great suffering of the animal.

Although a last resort, euthanasia may be the most humane treatment if our dog has degenerative myelopathy. Take a look at our article on euthanasia in dogs to learn more.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Degenerative Myelopathy in Dogs - Causes, Symptoms and Treatment, we recommend you visit our Neurological diseases category.