Equine Neurologic Diseases

Equine Herpesvirus Myeloencephalopathy (EHM or EHV-1)

Equine Herpesvirus Myeloencephalopathy (EHM) is a neurological disease of horses caused by Equine Herpesvirus-1, which can also cause respiratory disease, death in young foals, and abortion. This disease can be spread when horses gather for events such as parades, races, rodeos, and shows.

Spread

The virus can be spread in the air when an infected horse coughs or by nose-to-nose contact or equipment that comes in contact with the nasal secretions of an infected horse. Some horses may not have any signs of illness when spreading the virus.

Diagnosis and Treatment

If you suspect EHM, contact your veterinarian immediately. Horses can be tested by nasal swab or blood samples at the Utah Veterinary Diagnostic Laboratory or other laboratories. Affected horses are treated with fluids, antiinflammatories, and supportive care. Anti-viral medications may be used in some cases.

State Response Plan

Horses with EHM must be reported to the Utah State Veterinarian’s office by the owner, veterinarian, or laboratory. Owners with infected animals are placed under quarantine, and can be released from quarantine 21 days after the last animal displays signs of disease or after two sets of negative tests on all exposed horses.

Signs of EHM

Report these signs to your veterinarian:

• Eye discharge
• Unsteady gait
• Nasal discharge
• Weakness
• Dribbling urine
• Abortion
• Lack of tail tone
• Reluctance to rise
• Swollen legs

Protecting Your Horses

Before an Event

• Only take healthy horses to competitions.
• Ensure your horse is up to date on vaccinations.
• Clean and disinfect equipment before taking it to an event.

At the Event

• Limit horse-to-horse contact.
• Limit the number of people interacting with your horse. The virus can be transmitted on hands, clothing, and shoes.
• Avoid sharing equipment or supplies.
• Label supplies such as water bucket, feed bucket, brushes, and tack for each horse.
• Thoroughly clean and disinfect any shared equipment.
• Do not submerge hoses into water buckets.
• Discard unused feed, hay, and bedding on the event grounds.

After the Event

• Isolate horses that have been to an event from other horses on the home premises.
• Monitor your horse for signs of illness or temperature over 101.5ºF.
• Clean and disinfect any equipment that went to the show.