Neurological Horse Diseases

Horses are subject to neurological disorders just like any other animal. These diseases are typically caused by viruses or parasites called protozoa. Neurological diseases present many similar symptoms in horses, so testing is often required to properly diagnose and treat these ailments.

  1. Eastern and Western Equine Encephalitis Virus

    • Eastern and Western equine encephalitis infects horses when they are bitten by a mosquito carrying the virus. Symptoms of encephalitis include lethargy, muscle loss and lack of coordination. These conditions cannot be treated and can often result in death. Treatment typically involves managing the symptoms rather than curing the disease. Vaccines are highly effective, except in young foals whose immature immune systems cannot build up an immunity to the disease even after vaccination.

    Equine Herpes Virus Type 1

    • Equine herpes virus type 1 (EHV-1) usually begins as a respiratory infection but sometimes mutates into a disease that affects the central nervous system. Symptoms include weakness in the hind limbs, inability to urinate or defecate, or paralysis. This disease can result in death and can only be managed symptomatically once the animal becomes ill. Anti-inflammatory medications are often used to minimize damage to the spinal cord.

    West Nile Virus

    • West Nile Virus (WNV) is spread through an infected mosquito. WNV can produce a variety of symptoms, including violent behavior, toe dragging, lameness and fever. Approximately 50 percent of horses that contract West Nile will recover through supportive therapy and symptomatic treatment. A West Nile vaccine is available through your veterinarian.

    Equine Protozoal Myeloencephalitis

    • Equine protozoal myeloencephalitis (EPM) is a disease caused by four types of protozoa that affect the horse's central nervous system. EPM typically causes muscle loss, toe dragging and loss of coordination in the hind limbs. Prompt treatment of EPM with an anti-parasitic, aggressive drug program increases the chance of recovery. With proper treatment, 60 to 70 percent of horses make a significant or complete recovery. A vaccine for EPM is now available under a conditional license from the Department of Agriculture, and studies to determine its effectiveness are underway.

    Diagnosing Neurological Disorders

    • Testing to determine a horse's neurological disorder is very important. Because many neurological diseases present similar symptoms, testing cerebrospinal fluid is the most commonly recommended way to pinpoint the exact cause of symptoms. Identifying which neurological viruses or parasites are causing the horse's neurological symptoms ensures the appropriate treatment.