What is a "wobbler"?

The term "wobbler" is used to describe a horse which shows signs of poor co-ordination, muscle weakness or ataxia, especially affecting the hind limbs. The degree of abnormality may vary from barely perceptible right through the spectrum to extremely severe. In extreme cases, the horse may literally "wobble" and stagger when he attempts to move.

If you think your horse may be developing wobbler syndrome there are a number of common signs you should look out for. Have you noticed that your horse has begun to stumble more than usual when ridden? Has he started to over-reach or show abnormal wear of his front toes? Watch out for excessive tail movement when he trots or bunny hopping in the canter. Have you noticed an excessive knuckling of his hind legs as he stops or outward rotation of his hind toes when going uphill? Is he suddenly unable to change leads in canter?

The condition is caused by cervical stenosis. This means narrowing of the spinal canal in the horse's neck region. This narrowing causes pressure to be exerted on the spinal cord resulting in some or all of the symptoms described above. In sudden onset cases, check your horse over carefully. Could he have flipped over backwards or fallen whilst out in the field? He could have sustained a fracture of his cervical spine. Equine viral herpes and protozoa infections (commonly called EPM) can also cause damage to the spinal cord in the neck.

Although the horse's movement is controlled by the brain, it is actually finely co-ordinated by the nerves in the spinal cord. In the neck area, the nerves responsible for movement of the hind limbs are located toward the outside of the spinal cord making them vulnerable to damage when the spinal canal is narrowed.

Although younger horses are most commonly affected by the condition, it is very rare in foals and the most frequently diagnosed age group is from yearlings to four year olds. Older horses may present with similar symptoms but in the absence of any evidence of an accident, this is usually due to degenerative changes or arthritis in the joints between the vertebrae of the neck. Your vet will make a diagnosis based on clinical signs which will be confirmed by X-ray.

Diagnosis

In very mild, subtle cases, a myelogram may be used. Contrast materials such as barium are injected into the spinal canal. This will highlight any narrowing of the canal that may be present. In mild cases, a prolonged period of box rest and very restricted exercise may be sufficient to produce an improvement together with the administration of non-steroidal or corticosteroid anti-inflammatories.

In severe cases, the vertebrae of the neck may appear angulated against each other. This makes diagnosis straightforward. In these cases a wire frame, basket-like structure is inserted to stabilise the joint between the affected vertebrae. This surgery is not guaranteed to be effective but could serve to reduce the degree of incoordination and ataxia to such an extent that the horse may be saved and could even be deemed safe to ride.

Symptoms of wobbler syndrome may appear acutely, in some cases overnight. In other cases, symptoms may manifest themselves gradually over a period of time. Except in the very mildest of cases horses affected by wobbler syndrome are not suitable or safe to be used as riding horses. This is because there is too great a danger that they may fall, injuring not only themselves but also their rider.