Degenerative Myelopathy
Dogs diagnosed with DM are usually walking or wobbling before 5 years of age. Degenerative Myelopathy (DM) is a slowly progressive spinal cord disorder that resembles Amyotrophic Lateral Sclerosis (ALS or Lou Gehrig’s Disease) in people. The inevitable result for dogs with DM is paraplegia, either hind-end paralysis or both front and hind-end paralysis. If you want to purchase a puppy without this debilitating disorder finding a good breeder is key to eliminating this risk.
Most puppy mills will not do testing on their dogs even though they sell their French Bulldogs for over $2500. Testing the parents is a very small cost to eliminate the problems associated with poor breeding practices. Most quality breeders will have testing from parents and will give you a good guarantee with DM included in their agreement.
Symptoms of Degenerative Myelopathy
DM symptoms progress slowly over the course of months to years. They can start showing signs as early as 1 year and as late as 8 years old. From beginning to end, DM affected dogs typically remain alert and animated. The symptoms typically progress as follows:
Initial
- Loss of coordination (ataxia) in the hind legs
- Dragging the hind feet causing wearing down of the toenails.
- Hind-end weakness (difficulty climbing stairs, jumping up into the car, going for walks)
Intermediate
- Knuckling of hind feet (weight bearing on the tops of the feet rather than their undersides)
- Difficulty supporting weight with hind legs
- Inability to walk without support
- Urinary and/or fecal incontinence
Advanced
- Paraplegia (paralysis of hind legs).
- Weakness in front legs.
Although this degenerative process is not painful, affected dogs can develop discomfort because of overuse of other body parts attempting to compensate for the hind-end weakness. The difference between DM in physical pain vs. Arthritis pain is that the Frenchie is feeling pain in the areas of where the arthritis is present. In DM location there is just paralysis.
Cause of Degenerative Myelopathy
DM causes degenerative changes within spinal cord axons, structures that transmit information back and forth between the brain and the rest of the body. These degenerative changes begin in the thoracolumbar region of the spinal cord, the portion that lines up with the end of the rib cage. This explains why the hind limbs are more severely affected. Given enough time, the disease progresses toward the head end of the body, causing loss of front leg function as well.
DM is an inherited disease
The researchers discovered that DM has a recessive mode of inheritance. In order for a dog to be affected, the mutation must be inherited from both dam and sire. What remains unknown is why some dogs who have this “double mutation” never develop symptoms of DM. These dogs should never be used for a breeding program but can go 10 to 13 years of a quality of life without any signs or symptoms.
Genetic testing for Degenerative Myelopathy
Testing is available to determine an individual dog’s SOD1 mutation status. UC Davis veterinary genetics is where I have my testing done on my parents. I also will test every puppy before approving a breeder to my lines.
This DNA test identifies dogs that are normal (have two normal copies of the gene), those who are carriers (have one normal copy of the gene and one mutated copy), and those who are at risk for development of DM (have two mutated copies of the gene). It is important to remember that DNA testing does not diagnose DM. This is because not all dogs with two mutated copies of the gene go on to develop DM.
Responsible breeders utilize DNA testing for DM to help assess whether or not a particular dog is suitable for breeding purposes. Some puppy mills or back yard breeders do not test their breeding dogs and mating two dogs that have this gene will increase the risk of their offspring developing such issues.
Making the diagnosis of Degenerative Myelopathy
DM is a “rule out diagnosis”. What this means is that a presumptive diagnosis of DM can only be made by ruling out other causes of spinal cord disease (e.g., herniated intervertebral disk, tumor, infection, trauma). The only way to definitively diagnose DM is via a spinal cord biopsy collected through an autopsy (post-mortem) examination.
The diagnostics performed to rule out other causes of spinal cord disease often include:
- A thorough physical/neurological examination
- Blood and urine testing
- Advanced imaging (CT or MRI scan)
- Spinal fluid collection and analysis
Treatment of Degenerative Myelopathy
In veterinary research there is no known treatment capable of significantly altering the course of DM. When searching the Internet, one might find a number of approaches that have been tried or are recommended. Unfortunately, there is no scientific evidence that supports them. Many proactive preventive therapies for a dog that maybe susceptible to have the disease are the following:
- Daily exercise at least 30 mins daily of walking or playing
- Supplements for joints and skin
- Good nutrition program
- Therapeutic bed
- Massage
Prognosis of Degenerative Myelopathy
The quality of life for affected dogs can be enhanced through diligent nursing care, prevention of pressure sores, rehabilitation therapies such walking, swimming and stretching exercises, massage, acupuncture, and the use of specialized equipment such as booties, slings, harnesses, and wheelchairs to assist with mobility. These tools can help extend the dogs quality of life, however, DM progression does not stop the degenerative loss as the dog ages. The most common age of prognosis is around 5-7 years old. In some cases, it can be confused with arthritis or injury from jumping.
If there is any issue with immobility its best to have your vet eliminate health problems and come up with a plan for longevity of life with quality living as most important to your dog.
Source: “Genetics of ALS.” – The ALS Association. ALS Association, n.d. Web. 07 Jan. 2015. <http://www.alsa.org/research/about-als-research/genetics-of-als.html>.
