Rodeo fans and contestants were a little let down last week as the Double Bar G rodeo in Pine Bluffs, Wyo. cancelled its first show of the season.

The reason for the cancellation is because of the outbreak of a mutated strain of

the Equine Herpes Virus-1, a highly contagious disease that is spreading across several states, including Colorado, California, Utah, New Mexico, Texas and Washington.

Max Goodwine, of the Double Bar G rodeo says the decision to cancel was made out of necessity.

Goodwine says contestants are keeping their horses at home and the show would not have been well stocked.

"Everyone is keeping their horses at home to avoid coming into contact with this," Goodwine says, "We figured it would be easier and healthier to cancel."

Goodwine goes on to say that they will kick off the season on June 10. By then the quarantines will have expired.

Symptoms of the virus include fever, sneezing, staggering and partial paralysis. In some cases it can lead to death. The virus is highly contagious and can be spread by airborne transmission, horse-to-horse contact and by contact with nasal secretion on equipment, tack, feed and other surfaces. Caretakers can spread the virus to horses if their hands, clothing, shoes or vehicle are contaminated. Older horses are more affected by the virus. This disease poses no threat to humans.

The incubation period from exposur to the onset of signs is five to 14 days with most onsets occurring in 5-9 days.

According to Nebraska Veterinarian Field Officer Dr. Richard Perry, who covers a 15 county area in Nebraska, EHV1 is nothing new. However, what is surfacing now it a mutated version. And it is causing lots of trouble.

"Current vaccinations appear to be ineffective," Perry said.

Perry said the most devastating part of the disease is the neurological manifestation called Equine Herpes Virus Myeloencephalopathy, or EHM. When EHV1 manifest to EHM it often results in the euthanizing of the infected animal.

Horses infected with EHM show neurological signs, these include posterior incoordination, weakness, recumbency with inability to rise, and/or bladder atony. Confirmation of EHM requires a post-mortem examination.

A press release, dated May 13, 2011 from the Colorado Department of Agriculture stated that Colorado was investigating two confirmed cases of the virus.  The two horses were placed in quarantine on two Weld County premises.

Both of the diagnosed horses attended the National Cutting Horse Association's Western National Championship in Ogden, Utah.

Efforts have been made to contact anyone whose animals may have been exposed at that event. The NCHA has cancelled all events until June 3.

Of the 33 confirmed cases of EHV1 nationwide, 32 were at the Ogden, Utah event. Seven horses have died or have been euthanized because of the virus.

Five animals from Nebraska were at the event. Three returned to Nebraska and are currently under quarantine. The remaining two went on to Colorado to be with trainers. They are under quarantine there.

The quarantine is scheduled to last 21 days. This time frame is based on studies showing how long it takes horses to shed the virus.

Perry said there are no confirmed cases of the virus in Nebraska.

Since the outbreak, events in several states have been cancelled, and movement across state lines reduced.  At this time Nebraska has not altered the regulations on horses entering the state.

As of May 19, Wyoming had changed their entry regulations requiring an owner to have an official certificate of veterinary inspection within 72 hours of entering the state. The certificate must include temperature recorded for each horse listed. On the certificate must be the statements, "No horses listed have been exposed to any horse infected with or exposed to EHV1." and "No horses listed are showing any clinical signs of EHV1."

The order is scheduled to remain in effect until rescinded by the state. At this time Wyoming has one suspected but no confirmed cases of EHV1.

If you suspect your horse may have, or has come into contact with a horse, infected with EHV1 contact your vet right away.