It may all happen before you realise it- one day, your once lively and energetic dog begins to show subtle changes in their behaviour. Maybe they struggle to get up from their favourite spot, or their once graceful trot becomes increasingly unstable. It may seem as a harmless sign of aging at first, but can actually be the first indicators of a genetic condition known as degenerative myelopathy. Knowing the genetic status of your dog early on may point you towards recognising the symptoms as soon as they begin, and therefore seek appropriate care.

Degenerative Myelopathy (SOD1A) is a late-onset progressive degenerative neurological disease that affects the spinal cord. It is an autosomal recessive genetic condition- meaning that it requires two mutant copies of the gene to cause mutation, and therefore disease. It is also interesting to note that not all dogs that carry two copies of the mutant gene exhibit clinical symptoms in their lifetime. This can happen for various reasons; including the presence of modifying genes which may affect the symptoms that occur; or even environmental factors that play a role. While degenerative myelopathy may occur in any breed, certain breeds such as German Shepherds, Boxers, Rhodesian Ridgebacks, Burmese Mountain Dogs and Pembroke Welsh Corgis are genetically predisposed to the condition.

A single nucleotide mutation c.118G>A, in the SOD1 gene has been detected through genetic testing. The gene is responsible for encoding the superoxide dismutase 1 protein; and the mutation ends up causing a malfunction in the protein, resulting in an accumulation of toxic aggregates.

A dog’s central nervous system consists of neurons (which transmit nerve impulses over distances between neurons), which are protected by the myelin sheaths- a fatty, white layer- which also assists with the speed of transmission of the nerve impulses that move through the neurons. Bundles of axons (the tendrils that transmit nerve impulses between neurons) usually travel together and have a white appearance from the presence of the myelin sheath. Degenerative myelopathy results in these myelin sheaths wearing down, until they are eventually destroyed. This inhibits the nerves’ ability to transmit signals, which may eventually result in paralysis. The degeneration of the spinal cord leads to the presentation of clinical symptoms such as ataxia (progressive hind limb weakness and paralysis over time).

The onset of degenerative myelopathy is usually subtle, with early signs and symptoms such as the dog dragging their rear feet and having an unsteady gait caused by mild hind limb weakness. This progresses to a general loss of coordination- including swaying more often and falling over; as well as walking on knuckles and difficulty getting up. As the disease advances, the dog’s back legs get paralysed, which then eventually moves toward the front legs. This may progress to the head. As paralysis sets in; it may also lead to urinary and faecal incontinence.

Diagnosing degenerative myelopathy requires a full evaluation by a veterinarian. Diagnostic tests will be necessary to rule out other conditions and therefore confirm the diagnosis. Genetic testing is also helpful as it can identify whether your dog carries the SOD1A mutation.

While there is no cure for degenerative myelopathy, supportive care and management strategies can help with improving your pup’s quality of life. Physical therapy, medications, and assistive devices to support dogs with weakened hind limbs are just a few options that can assist in making your pup’s life as comfortable as possible.

Knowing the genetic health status of your canine companion should be a priority to ensure the health and happiness of your pet and to give you peace of mind.

Where can I get genetic health tests done?

At ZooOmics, we provide both health and colour testing as well as DNA profiles for both canine and feline. We utilise innovative technology to perform mutation testing and provide certificates for all testing, which can be submitted to registrars and breed societies.

For inquiries about sample collection, shipping, processing, and services, please contact us at info@ZooOmics.co.za. Alternatively, visit our website at www.zooomics.co.za to download our sample submission form.