Degenerative Myelopathy

Degenerative Myelopathy (DM) is a progressive, fatal neurodegenerative disease affecting the spinal cord of dogs. It is analogous to Amyotrophic Lateral Sclerosis (ALS) in humans. The disease causes progressive loss of coordination and strength in the hind limbs, eventually leading to complete paralysis. A mutation in the SOD1 gene is associated with the condition.

Symptoms & Signs

• Progressive hind limb weakness
• Knuckling of the hind paws
• Dragging of the hind feet (scuffed nails)
• Difficulty rising
• Swaying gait
• Loss of muscle mass in hind limbs
• Fecal and urinary incontinence (late stage)
• Eventually affects front limbs

Causes & Risk Factors

Associated with a mutation in the superoxide dismutase 1 (SOD1) gene. Homozygous (two copies) dogs are at risk, though not all develop clinical disease. The mutation leads to progressive demyelination and axonal degeneration in the spinal cord.

Diagnosis

Diagnosis of exclusion: MRI to rule out compressive spinal cord disease, CSF analysis to rule out inflammation. DNA testing for SOD1 mutation supports clinical suspicion. Definitive diagnosis requires post-mortem histopathology.

Treatment

No cure or effective treatment exists. Supportive care includes physical rehabilitation, hydrotherapy, assistive devices (harnesses, wheelchairs), and maintaining quality of life. Some evidence suggests intensive physiotherapy may slow progression.

Prevention

DNA testing breeding stock for SOD1 mutation. Avoiding breeding two carriers together. Genetic counseling for breeders of affected breeds.

Prognosis

Progressive and ultimately fatal. Most dogs are euthanized within 6-36 months of diagnosis due to quality of life concerns. The disease is not painful but profoundly affects mobility and independence.

Affected Breeds (6)

Related Conditions

• Intervertebral Disc Disease
• Lumbosacral Stenosis
• Spinal Tumors