Many of you will be familiar with Equine Wobbler Syndrome, when a horse displays varying degrees of hind limb and sometimes fore limb ataxia. This condition often first manifests in the young growing animal and is caused by compression of the cervical spinal cord. Malformation or instability of the vertebrae can lead to the cord being effectively” pinched” resulting in the patient being unable to coordinate his limbs properly. The developmental bone disease OCD can also be involved resulting in areas of abnormal bone being produced at the margins of the spinal canal. Clearly some cases can also result from trauma such as a fall or the horse having a collision.
The gold standard of diagnosing these cases is to perform a CT myelogram under general anaesthesia so that a 3-D image of the spinal cord can be obtained. This equipment is not widely available and the whole procedure is expensive to carry out and not without risks to the patient. The next best diagnostic technique has been to do a contrast myelogram using radiography again under general anaesthesia. As you can imagine with either option, recovery of an ataxic horse from a general anaesthetic is not always straightforward. The contrast is a sterile fluid which is radio-opaque, meaning that it shows up on x-rays and has to be injected directly into the spinal canal.
At Peasebrook we recently carried out a standing myelogram using radiography in a sedated patient. We used a novel approach to inject the contrast material into the spinal canal between the first and second cervical vertebrae under ultrasound guidance. The patient, a two year old thoroughbred colt tolerated the procedure perfectly and we obtained some excellent diagnostic images. We only injected a small amount of contrast in this case as we were trialling the technique but as you will see from the images, the spinal cord is highlighted well. This represents a much more economic diagnostic than the general anaesthetic options and without the risk of injury during recovery.
Lateral radiograph of the neck prior to injection of the contrast material
Lateral radiograph of the neck after injection of contrast showing delineation and impingement of the spinal cord within the canal.