A part of the wider Developmental Orthopaedic Disease complex, Wobblers have malformation of the cervical spinal vertebrae causing compression of the spinal cord through narrowing of the spinal canal. Symptoms relate to the interference in nerve transmission between the brain and limbs via the compressed spinal nerves. Consequently, affected horses exhibit poor control of the hind limbs especially, and sometimes the forelimbs. They show a swaying gait, may stumble, fail to pick up their feet normally and often wear their hooves at the toes. When handled they have difficulty backing and turning in tight circles. In effect they do not know where their feet and limbs are – a defect in proprioception and have trouble controlling the muscles required for normal movement. In some, there is neck pain and stiffness with difficulty rising and reluctance to move.
The disease typically begins to manifest itself by around 6 months age but can show any time up until three years old or older. Fast growing Thoroughbreds are most commonly affected with an incidence estimated at 2%-3%. Diagnosis is based on clinical signs of ‘’wobbling’’ confirmed by radiography of the neck, possibly including the use of contrast medium injected into the spinal canal to highlight the narrowing and cord compression. CT scans may be employed if available.
Medical treatment revolves around controlling inflammation and spinal arthritis at the site of the vertebral defect(s) which may include local injection of corticosteroid drugs into the spinal joints. In young horses dietary management includes restricting carbohydrate and protein intake to reduce rapid growth rate whilst maintaining adequate mineral, trace element and vitamin nutrition.
In mild cases in younger horses surgical intervention may be attempted with the use of metal bone baskets containing bone graft material harvested from the pelvis and fixed into position between adjacent vertebrae after drilling a suitably positioned cavity to accept it. The aim is to stabilize the vertebral bodies and prevent further movement and cord compression. Up to 12 months may be necessary to fully evaluate response to such surgery but around one third of suitably selected surgical candidates will improve sufficiently to perform athletically. Affected horses should probably not be bred as there is likely some genetic component to the condition, just as there is for D.O.D. in general.