Spinal cord disease in horses is fairly common, but it can be difficult to precisely diagnose. Ancillary tests such as cerebrospinal fluid analysis, contrast myelography, and electromyelography can be helpful, but also somewhat risky. There is another diagnostic technique used in humans that is not painful and has no serious side effects. The technique is called transcranial magnetic stimulation, and it uses a magnetic coil stimulator to produce electrical signals that can be recorded on paper. These signals are called magnetic motor evoked potentials (MMEPs); they change when spinal cord disease is present. Researchers from the University of Ghent in Belgium set out to evaluate this test for possible use in horses with signs of spinal cord disease.

First, transcranial magnetic stimulation was performed on 12 healthy horses to establish normal reference tracings of MMEPs. Next, the test was performed on 12 ataxic horses suspected to have spinal cord injury or disease. When tracings from both groups were compared, several features of the MMEPs were consistently different in the ataxic horses. Even more significant, MMEPs from ataxic horses remained abnormal even after the horses recovered. In other words, this technique could also be used to detect old, healed lesions in the spinal cord of horses with little or no clinical signs. Transcranial magnetic stimulation is a sensitive, safe, and painless procedure for evaluating horses with signs of spinal cord disease.

Nollet, H.; Deprez, P.; Van Ham, L.; et al. Equine Veterinary Journal, 34 (2), 156-163, 2002