For horse lovers in the Western states, summer is a time of rodeos and horse shows. But an outbreak of the equine herpes virus has claimed the lives of several horses and forced the cancellations of numerous events. Here, a brief guide to the threat:

What is happening?
There has been an outbreak of equine herpes in at least six Western states — California, Colorado, Arizona, Idaho, Utah, and Washington — and Canada. "People in the horse world are freaked," says one anonymous industry insider. Several equestrian competitions and shows have been canceled, just as the season for such events is ramping up. It's unclear how many horses have been infected, but at least 17 cases have been noted. The majority of those cases were horses that attended a National Cutting Horse Association championship in Ogden, Utah, earlier this month.

What are the symptoms of herpes in horses?
They include nasal discharge, fever, coordination issues, lethargy, urine dribbling, weakness in the hindquarters, and inability to stand up. Sometimes infected animals need to lean against a fence or wall for balance.

How is it transmitted?
The highly contagious disease can be passed from horse to horse through contaminated tack (saddles, bridles, etc.) and clothing. The virus can typically survive about a week on a surface, but in the right conditions, it can live for a month. This makes it quite tricky to fight, says Debra Sellon, a vet with the Washington State University Veterinary Teaching Hospital. If an infected horse sneezes on a piece of equipment or bale of hay, the virus could be transmitted to another horse days later.

Can humans catch it?
No, humans cannot contract the equine herpes virus (EHV-1). They can, however, transmit it between horses via contaminated equipment or clothing.

How is it treated?
There is no cure for the virus, but the symptoms may be treated. It can, however, be deadly, and horses that are no longer able to stand are euthanized. Of the 17 cases reported, at least three have been fatal.

How bad could this get?
While the outbreak has been confined to the West, officials say it could easily grow to a national threat. As a result, infected horses are being quarantined.

Sources: Reuters,, Veterinary News