Stumbling, weakness, toe dragging, difficulty going downhill, inability to change leads… these gait abnormalities are commonly due to lameness, but occasionally neurologic disorders are the cause. In New Zealand, we are fortunate not to have many of the infectious agents that cause neurologic disease in horses. However, we do see Cervical Vertebral Stenotic Myelopathy (CVSM), a.k.a Wobblers Syndrome.
What is CVSM?
CVSM occurs when the spinal column in the neck (vertebrae and ligaments) impinge and compress the spinal cord. There are multiple causes but the most common are vertebral malformation in young, rapidly growing horses and arthritis in older horses. It may seem unusual that dragging of the hindfeet is due to a problem in the neck, but this is because the nerves that travel between the hindlimbs and the brain are located superficially in the region of the spinal cord that is prone to being compressed.
When your horse has a gait abnormality a thorough lameness and neurologic examination is the first step to provide a diagnosis, a treatment plan, a long-term prognosis and (importantly) an assessment of whether the horse is safe to ride. If neurologic deficits are detected, radiographs of the neck can help to assess if CVSM could be the cause.