Equine herpes virus outbreak spreads; 29 cases now confirmed in eight Western states, veterinary officials report

National Report

— An outbreak of equine herpes virus (EHV-1) continues to spread with at least 29 cases now confirmed in eight Western states.

Various state agriculture departments report that about 400 horses from 29 states attended the National Cutting Horse Association's Western National Championships in Odgen, Utah between April 30-May 8, which is believed to have been the source of the outbreak.

On May 19, Washington officials increased the state's confirmed case count from one to three. Other cases have been confirmed in multiple western states, but taper off north of Texas and further east. As of May 19, the following states, through their state veterinarian's office or agriculture department, have confirmed or suspected equine herpes virus cases:

• Arizona — One confirmed case;

• California — 10 confirmed;

• Colorado — Six confirmed cases; five that attended the NCHA event and one that was in contact with sick horses but did not attend the event;

• Idaho — Two dead, no confirmed cases;

• Montana — 30-35 horses under observation, no confirmed EHV-1 cases reported;

• Nebraska — Five farms quarantined, no cases confirmed;

• Nevada — No confirmed cases;

• New Mexico — One dead, one suspected and no confirmed cases;

• Oregon — One confirmed case;

• Texas — 20 under investigation. The one confirmed case was a horse from New Mexico that was taken to West Texas for treatment.

• Utah — Five confirmed cases;

• Washington — Three confirmed cases;

• Wyoming — No confirmed cases.

Colorado State University, Washington State University and the University of California-Davis all have restricted equine access at their veterinary hospitals in response to the outbreak.

The California Department of Food and Agriculture stated that there is no evidence the disease has spread beyond horses exposed at the Utah competition. However, Colorado veterinary officials report that at least one horse was confirmed positive following viral exposure from other horses attending the Utah event.

While most states have not reported any change in equine movement protocols, Wyoming, which has not reported any confirmed cases, now requires an official certificate of veterinary inspection 72 hours prior to entry into the state. The certificate must include the horse’s temperature and statements that they were not exposed, infected or showing any clinical signs of EHV-1 at the time of inspection. The order, put into effect May 19 by State Veterinarian Dr. Jim Logan, will remain in effect until further notice, according to the Wyoming Livestock Board.

The U.S. Department of Agriculture also is monitoring the outbreak, with each state submitting weekly reports. USDA is reportedly compiling a national report on the EHV-1 outbreak.

Horse owners are being advised to notify veterinarians if they participated in the NCHA event or if their horse suddenly comes down with a temperature above 102-degrees-F, which typically precedes clinical signs, veterinarians say.