Degenerative Myelopathy Testing Guide for Dogs

Degenerative myelopathy (DM) is a progressive neurological disorder in dogs marked by a gradual decline in coordination and strength, initially impacting the hind legs and potentially leading to paralysis. This genetic disease stems from mutations in the SOD1 gene and is identified in over 40 recognized dog breeds in the United States, though its effects can vary significantly between breeds. For breeders and pet parents, understanding and utilizing genetic testing can play a crucial role in minimizing DM's spread in future generations.

What is Degenerative Myelopathy in Dogs?

DM involves deterioration of the spinal cord, causing dogs to slowly lose strength and coordination in their hind limbs. Early symptoms often include dragging or scuffing one or both back paws, combined with general weakness, which may progress over months or years to complete paralysis. In more advanced phases, the disease might affect the front legs, nerves controlling facial muscles, and breathing muscles. Since there is currently no cure, ethical euthanasia is sometimes considered when a dog's quality of life declines severely.

Typical onset of symptoms occurs later in life, usually between 8 to 10 years old, which complicates early detection as many dogs may already have been bred by then. The progression speed varies; some dogs become paralyzed within a year of symptom onset, while others exhibit a slower decline.

Breeds Commonly At Risk for DM

The mutation in the SOD1 gene is present across multiple breeds, but a smaller number show a higher risk. Notable American breeds include the French Bulldog puppies, German Shepherd puppies, Pembroke Welsh Corgi puppies, Boxer puppies, Chesapeake Bay Retrievers, and American Eskimo Dogs. These breeds warrant particular attention to genetic screening to avoid passing on the mutation.

How Degenerative Myelopathy is Inherited

DM follows an autosomal recessive inheritance pattern, meaning a dog must receive two copies of the mutated SOD1 gene (one from each parent) to be at high risk of developing the condition. Dogs receiving only one mutated gene copy are carriers; they typically exhibit no symptoms but can pass the mutation to their pups.

Breeding two dogs clear of the mutation results in litters free of DM. However, pairing two affected dogs leads to all offspring being at risk. When one or both parents are carriers, there's a chance of producing affected or carrier puppies, underscoring the importance of genetic testing in breeding decisions.

Getting Your Dog Tested for Degenerative Myelopathy

DNA testing for DM is vital, especially for owners and breeders of susceptible breeds. Because symptoms manifest late, a dog might appear healthy yet carry or be at risk for the disease.

Step 1: Talk to Your Veterinarian

Ask your veterinario to perform a genetic DM test. Samples are usually collected through a simple blood draw or cheek swab, both minimally invasive methods.

Step 2: Laboratory Analysis

Your sample will be sent to a certified lab, such as those at the University of Missouri, UC Davis Veterinary Genetics Laboratory, or private companies like AffinityDNA. Results typically take 7 to 10 business days. Testing costs generally range from $69 to $75 in the US.

Step 3: Understanding Your Results

Test outcomes will categorize your dog as:

• Clear: No copies of the mutated gene detected
• Carrier: One mutated gene copy, usually asymptomatic but can pass it on
• Affected: Two mutated gene copies, high risk of developing DM

Use this information to guide breeding choices responsibly or anticipate care needs if your dog is affected.

The Importance of Ethical Breeding Practices

Screening breeding dogs to ensure clear status or avoiding breeding two at-risk parents can significantly reduce degenerative myelopathy in future litters. Responsible breeding helps preserve breed health and demonstrates dedication to high ethical standards.

Summary and Advice for Dog Owners

Genetic testing for degenerative myelopathy is a crucial tool in promoting canine health, especially for breeds known to carry the mutation. Early testing combined with veterinary insights allows informed decisions that limit the disease’s spread.

When searching for a new puppy, look for reputable breeders who provide health clearances and testing results, giving your new family member the healthiest start possible.

In the end, knowledge and proactive measures empower dog lovers and breeders to enhance quality of life for their pets and reduce hereditary diseases.