Degenerative myelopathy (DM), also known as chronic degenerative radiculomyelopathy or German shepherd degenerative myelopathy, is a progressive spinal cord disease that affects dogs, leading to hind leg coordination loss and eventual paralysis. This condition arises from the degeneration of structures within the spinal cord responsible for nerve impulses, causing hindquarters weakness and hindleg paralysis. In this article, we will delve into the causes, symptoms, diagnosis, and management of DM in our canine companions.
The Degenerative Process
DM develops due to a DNA mutation in the superoxide dismutase 1 (SOD1) gene, identified in 2009. While it is more common in certain breeds, such as German Shepherds, it can affect others, like American Water Spaniels, Bernese Mountain Dogs, Boxers, and Pugs. Typically, DM is observed in dogs between 8 and 14 years old.
Symptoms and Diagnosis
The disease begins gradually, with initial signs resembling hip dysplasia, including difficulty getting up and an unsteady gait, especially on smooth surfaces. Over time, dogs may drag their hind leg feet or "scuff" their hind limb toenails. The hind legs may crisscross while standing or walking, and muscle wasting in the rear limbs becomes evident. As DM progresses, front leg weakness may occur. Fortunately, dogs with DM do not experience pain.
Diagnosing DM requires ruling out other diseases with similar symptoms, such as herniated disks, cancer, infection, or spinal stenosis. A combination of physical and neurological examinations, blood work, radiographs, myelography, spinal fluid analysis, and CT or MRI scans is often necessary. However, a definitive diagnosis can only be made postmortem by examining spinal cord biopsy samples.
Management and Treatment
While there is no cure for DM, supportive treatment can help manage the disease. Exercise, like walking and swimming, should be encouraged, and physical therapy can help maintain muscle mass and improve the dog's quality of life. A study showed that dogs receiving intensive physiotherapy lived longer and maintained mobility better than those with moderate or no therapy.
Once dogs reach the non-ambulatory state, owners should be prepared for pressure sores, urine leakage, and loss of bowel control. A combination of epsilon-aminocaproic acid, N-acetylcysteine, prednisone, vitamins B, C, and E, along with exercise therapy, has been suggested to slow the disease's progression, but the benefits are not conclusive.
Breeding and Prevention
Since DM is linked to specific breeds, responsible breeding is essential for prevention. If acquiring a purebred puppy of an affected breed, inquire about the kennel's DM history in their line. Understand that clinical signs may only appear long after sexual maturity.
While the DM gene mutation is common in some breeds, overly aggressive breeding programs to remove the mutation may lead to other health risks and eliminate other desirable breed qualities. A realistic approach involves considering the DNA DM results as one would evaluate any other undesirable trait or fault.
Prognosis
Sadly, most affected dogs are euthanized due to disability within 6 to 12 months of symptom onset. Proper management and supportive care can improve their quality of life, but the disease's progressive nature poses significant challenges for affected dogs and their owners.
Degenerative myelopathy is a heart-wrenching disease that affects our beloved canine companions, leading to hind leg coordination loss and paralysis. While there is no cure, early diagnosis, and proper management can improve the dog's comfort and extend their mobility. Responsible breeding practices can help prevent DM from impacting future generations. As devoted pet owners, we can offer our dogs the care and support they need during their battle with this devastating disease.
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