February 28, 2019 – For nearly three decades, Morris Animal Foundation has supported research on degenerative myelopathy (DM) in dogs. Older, large breed dogs are most commonly affected by this terrible disease although the disease can affect small breed dogs, notably Pembroke Welsh corgis.
This chronic, progressive condition destroys the spinal cord causing a slow deterioration of function in the rear legs, ultimately resulting in paralysis. The disease is challenging to diagnose and currently has no cure. Many dog owners opt for euthanasia once paralysis sets in, usually within a year of diagnosis.
Morris Animal Foundation’s early work tried to pinpoint causes for DM, from vitamin deficiencies to viral infections, but to no avail. Because the disease is more common in certain breeds of dogs, an underlying genetic component was strongly suspected. Veterinary researchers found a clue to understanding DM by noting similarities between DM and an equally devastating disease in people – amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease.
In the early 1990s, researchers discovered a mutation in the SOD1 gene associated with ALS. Today, researchers know a mutation in the SOD1 gene also is a major factor contributing to the development of DM in many dog breeds. In addition, recent research has identified a unique mutation of the SOD1 gene that seems unique to Bernese mountain dogs.
A screening test for SOD1 is available to identify genetic status of breeding dogs and help reduce disease risk to their offspring. Two mutated copies of SOD1 (one from each parent) increases risk for DM but not all dogs with two copies of the mutation will develop the disease. Experts suggest that other genetic or environmental factors also are critical to the development of the disease.
What Pet Owners Should Know
- DM usually affects older dogs (at least 8 years old).
- Disease progresses more slowly in small breed dogs.
- Progression of disease is highly variable.
- Early clinical signs include muscle weakness and lack of coordination.
- Immediately consult with your veterinarian if your dog drags one or both rear paws when it walks.
Morris Animal Foundation currently is funding two studies to help solve the diagnostic and treatment challenges of this devastating disease in dogs.
Imaging for Improved Diagnosis
Diagnosis of DM currently relies on neurological clinical signs and a positive SOD1 genetic test. Researchers noted that white matter lesions are linked to a genetic mutation in SOD1. However, commonly used diagnostic tools such as X-rays, magnetic resonance and spinal fluid analysis have all fallen short in definitively diagnosing this disease. Our funded researchers are gathering data using a different type of imaging technology, diffusion tensor imaging, an advanced MRI technique that may help detect white matter lesions within the spinal cord. This approach successfully is used to detect white matter lesion load in human patients with neurodegenerative disease. Early data using this new imaging technique in dogs is promising.
Commercially available treatments and therapies to stop degenerative myelopathy in its tracks simply don’t exist. Currently, we are funding research using a new gene silencing technology to help prevent the buildup of SOD1. In a small clinical trial enrolling four client-owned dogs with degenerative myelopathy, researchers are seeing if they can reduce the expression of the mutation in the SOD1 gene using this new technology. If effective with no adverse results, researchers will explore this strategy further as a potential novel therapy for dogs with degenerative myelopathy.
Morris Animal Foundation is dedicated to helping researchers through the discovery process that sometimes takes years and even decades until a breakthrough is found. We are champions of finding solutions for complex animal diseases, such as degenerative myelopathy, that have few or no available treatments or therapies. We fund everything from bench science (trying to learn about the disease process and potential therapy targets), all the way to viable products and techniques for veterinarians to use in their clinics to better care for your pets. And we never give up.
Visit Morris Animal Foundation to learn more about degenerative and other diseases in dogs and how you can support the discovery process to make sure dogs live longer and healthier lives.