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Caution Urged in Response to Equine Herpesvirus (EHV-1) Outbreak

More than forty horses in the western U.S. have been diagnosed with Equine Herpesvirus (EHV-1) after attending the National Cutting Horse Association Western National Championships in Ogden, Utah between April 29th and May 8th. At this point, confirmed or suspected cases have been reported in Arizona, California, Colorado, Idaho, New Mexico, Oregon, Texas, Utah, Washington, plus Alberta, but veterinary health officials in other states are watching closely. Horses from at least 29 states and provinces attended the event in Ogden. 

The National Cutting Horse Association reported that show producers have voluntarily cancelled upcoming sanctioned events in the interest of horse health. As of today, show cancellations have been announced in at least ten states and provinces. While precautions vary among the affected jurisdictions, horses in most states that have been in contact with an infected horse and show signs or test positive are being placed under quarantine to limit the spread. In addition, many facilities and individual owners are restricting movement and taking other precautions on their own to protect their horses.

There are no reported or suspected cases in Michigan at this time, so the risk of infection is low. However, if your horse or other horses at your barn attended the NCHA Western National Championships, you should monitor them very carefully for 21 days. Your veterinarian can test for EHV-1 and can give you anti-viral drugs if your horse is infected.

Owners with horses that have potentially been exposed are urged to take temperatures on each horse twice a day. Temperatures above 102F should be reported to your veterinarian immediately for evaluation and laboratory testing. The Equine Herpes virus is extremely contagious and can spread quickly among horse populations.

EHV-1 can not be transmitted to humans. Horse-to-horse contact, aerosol transmission, contaminated grooming equipment, hands, clothing, boots, tack and feed can all play a role in spreading the disease through horse populations. Infected horses with this neurologic strain of EHV-1, may show any of the following clinical signs: hind-end weakness, nasal discharge, decreased coordination, lethargy, recumbency (frequent or constant lying down), urine dribbling and diminished tail tone. There is no specific treatment and there is no equine vaccine for protection against this neurologic strain.

Most importantly, you should practice sound biosecurity measures to prevent infectious disease spread. Among others: hand washing in between handling horses, don't share equipment or feed/water buckets between horses; change your clothes and boots after handling sick horses; and disinfect areas and equipment exposed to sick equines including stalls, tack, and trailers.