Degenerative Myelopathy in Dogs
Canine degenerative myelopathy is an incurable progressive disease of the canine spinal cord that shares many similarities with the human disease amyotrophic lateral sclerosis ALS, also known as Lou Gehrig's disease. You may remember ALS from the viral ice bucket challenge videos that were circulating around social media a few years ago. In dogs, degenerative myelopathy (DM) affects the spinal cord and causes weakness in the hind limbs, which progresses into their full paralysis.
Degenerative myelopathy is usually diagnosed in middle-aged or older dogs, and it can often be mistaken for arthritis or other joint issues in the earlier stages. In larger dogs, DM usually manifests around 8 years of age, but in smaller breeds it may not show up until into their second decade. On rare occasions, very young dogs have also presented with DM. Degenerative myelopathy in dogs is non-reversible and follows a progression through three distinct phases (early, intermediate, advanced) although the duration of each phase can vary widely.
What Causes Degenerative Myelopathy?
The exact cause of DM has not been determined, but scientists have traced its occurrence to the existence of the genetic mutation in a gene called superoxide dismutase 1 (SOD-1). According to our current understanding, a dog must have two copies of the mutated Gene in order to develop DM. However, there are some dogs with two copies of this gene mutation that do not develop DM.
Genetic Test for Canine Degenerative Myelopathy
Genetic testing is available through the Orthopedic Foundation for Animals in order to identify whether a dog has this gene mutation. This DNA testing uses saliva to help identify whether a dog has an elevated risk of degenerative myelopathy as well as whether or not they are a carrier for this disease.
# of SOD-1 Mutation(s)
Dog is clear of DM
Dog is carrier of DM
Dog at high risk for developing DM
This genetic screening is only recommended for predisposed breeds, but can be performed on any dog using a sample collected from swabbing the inside of the cheek.
Breeds affected by DM
DM is significantly more prevalent in certain dog breeds including German Shepherds, German Shepherd mixes, Siberian Huskies, and Collies. Recently, elevated risk status has been expanded to include a number of additional breeds including: Bernese Mountain Dogs, Boxers, Golden Retrievers, Chesapeake Bay Retrievers, Rhodesian Ridgebacks, Kerry Blue Terriers, Pembroke Welsh Corgis and more.
Phase One: Early DM Signs
Chronic degenerative radiculomyelopathy (CDRM) symptoms in dogs are caused by the deterioration of the white matter of their spinal cord.
Early symptoms you may find in a dog with degenerative myelopathy include:
- Lack of balance/coordination or other signals of instability i.e. falling when pushed gently from the side
- Difficulty getting to standing position after lying down
- One or both of hind paws turns inward, giving the appearance of a dog walking on knuckles
- Loss of muscle in rear legs
The presence of one or more of these does not mean that your dog definitely has degenerative myelopathy as there are other spinal cord diseases that may have similar presentation.
Phase Two: Intermediate DM Signs
Clinical signs of canine degenerative myelopathy that has progressed to the second, intermediate, stage include:
- Assistive mobility device needed for walking
- Muscle atrophy/ severe in hind limbs
- Rear body has “sagging” appearance from combination of muscle loss and body’s struggle to support weight
- Balance and coordination difficulties
- Knuckling of rear paws when standing or walking
- Limp tail
- Urinary / fecal incontinence may start to present
Phase Three: Advanced DM Clinical Signs
Dogs in the final stages of advanced DM show many signals of their body’s decline as the disease’s grasp extends to the rest of the body with symptoms including:
- Erratic motions of the tail and rear legs
- Front legs and shoulders also show weakness
- Complete paralysis of rear legs
- Total loss of continence
- Respiratory issues
- Organ failure
- Complete lack of coordination
- Assistance needed for all movement
Bowel and Bladder Problems
While a dog may retain its ability to control urination and defecation during the earlier phases of phases of degenerative myelopathy, they will eventually lose these functions as the disease progresses to paralysis. Initially this may present as the occasional accident and over time will develop to full loss of continence -- urinary and fecal.
Diagnosis of DM and Treatment
If a dog is displaying any of the troublesome health problems outlined above, it should be promptly evaluated by a licensed veterinarian to rule out other causes like arthritis and hip dysplasia. In some dogs, both DM and these conditions are present, Myelopathy degenerative is diagnosed using a combination of genetic testing, health history, x rays, and physical evaluation of the dog’s hind end.
Veterinary Treatments for Degenerative Myelopathy DM
Currently, there is no veterinary treatment or cure for degenerative myelopathy in dogs. However, treating any comorbid conditions (like arthritis or hip dysplasia) can reduce DM symptoms, provide pain relief, help keep your dog as mobile as possible and improve their overall quality of life. Diet and exercise are critical in dogs with DM, especially preventing obesity, which adds additional stress on the spine and joints. Physical Therapy can be used to prolong quality of life as well as protect muscle mass in dogs with DM. Research shows that clinical signs of the progression of DM can be slowed with a combination of vitamins, corticosteroids like prednisone, and exercise therapy.
Quality of life for Dogs with DM
Diagnosis with a degenerative disease or condition does not have to signal the end of your happy relationship with your pet. Great advances have been made in the technology used for assistance devices, which can help a dog retain some mobility after its legs have been weakened/paralyzed. Many dogs are unable to walk within 6 to 9 months of this disease’s onset. Many dogs are quick to adjust to the new routines and devices associated with DM. Maintaining an open dialogue with your vet is crucial to your pets quality of life.