Degenerative myelopathy

DEGENERATIVE

MYELOPATHY

A DEVASTATING SPINAL CONDITION

Degenerative myelopathy, commonly known as Degenerative Radiculomyelopathy (CDRM) is a spinal disorder most commonly affecting breeds like the German Shepherd. It has recently also been diagnosed in Corgis, Poodles, Pugs, Boxers, Rhodesian Ridgebacks and Retrievers, with the average age of onset of clinical signs occurring between 7 and 14 years of age.

DNA testing can identify the mutation in the gene.

WHAT IS DEGENERATIVE MYELOPATHY?

Degenerative myelopathy is a neurological condition that slowly progresses over several months (usually 12-18 months from the first onset of signs). In this condition, the nerves of the spinal cord gradually lose their myelin coating (demyelinate), which reduces their ability to transmit nerve impulses. The condition generally begins in the middle of the back and then spreads throughout the rest of the spine. It is not, in itself, painful but will gradually result in complete hind limb paralysis.

The cause of the condition is not fully understood, but there does seem to be a genetic link involved. The link comes in the form of a mutation in the gene coding for superoxide dismutase, a protein responsible for destroying free radicals in the body. Free radicals are needed as part of a natural defence system in the body but can become harmful when produced in excessive quantities. In excess, they can cause cell death and degenerative diseases. It seems that inheriting one copy of the mutated gene from the father and one from the mother is strongly associated with the development of degenerative myelopathy. However, having two copies does not necessarily always result in clinical disease, and similarly, an absence of the gene mutation does not guarantee that the condition will not occur. Interestingly, the same gene mutation is also found in a form of motor neuron disease in humans.

Degenerative myelopathy sees the myelin coating of the nerve break down. Myelin is critical for efficient transmission of nerve signals.

CLINICAL SIGNS OF THE DISEASE

Clinical signs of degenerative myelopathy include: • General weakness in the hind limbs • Scuffing of nails caused by dragging of the paws • Stumbling, especially on slippery surfaces • Ataxia (a wobbly and uncoordinated gait), particularly in the hind limbs • Muscle atrophy over the hind limbs • Delayed proprioception (i.e. delayed ability to sense where the limbs are) • Incontinence • Hind limb paralysis

DIAGNOSIS

Your vet will examine your dog and investigate to rule out other causes of the symptoms, like a slipped disc. In some cases, your dog may be referred to a neurology specialist for further tests and confirmation of the diagnosis.

TREATMENT

With the condition being progressive and damage being irreversible, there are, unfortunately, no current surgical options available. Owners whose dogs have been diagnosed can therefore only provide support to their companion and give them a good quality of life for as long as possible. Complementary therapies can aid in improving quality of life and include: • Massage therapy eases any compensation over the forelimbs caused by the shoulder muscles becoming tense from having to do extra work and also helps to ease tension in the lower back, as this area is put under stress when the hind limbs are failing. • Hydrotherapy helps mobility and provides non-weightbearing exercise to encourage muscle tone to remain as high as possible for as long as possible. It also helps to promote normal limb placement. Other ways to help a dog with degenerative myelopathy include: • Providing softer bedding for greater support. • Using paw boots to protect the feet, especially the hind limbs. • Using a harness for extra support when walking. • Controlling the weight of the dog to avoid unnecessary stress on the body.

Some companies make braces and even carts with wheels for dogs with the condition.