As the illness progresses the brain stem and spinal cord are affected. Muscle weakness becomes apparent and there are behavioral changes and dementia. Notable symptoms aggression, head pressing, wall leaning, compulsive circling, and blindness. Other signs might include uncontrolled twitching of the eyeball, and facial muscle paralysis. As the disease progresses, a semi-comatose and convulsive state occurs.
Death usually follows two or three days later.
If the animal survives, residual nervous system problems result. Encephalomyelitis vaccines are available for horses from several different companies. They are packaged as single or combination vaccines. All unimmunized horses are at risk regarding this disease. Speak to your vet today if you are unsure about your horse's vaccination history.