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"Credible reports" indicate six states involved in EHV-1 outbreak

May 18, 2011

» Latest on this outbreak

"Credible" reports indicate cases of Equine Herpesvirus 1 in six Western states and Western Canada, according to the National Cutting Horse Association.

Electron micrograph of EHV-1.

Death toll

As at 25.6.2011

New Mexico
About EHV

The association said "credible, but not official" reports indicate cases in Colorado, Utah, California, Washington, Oregon, Arizona and Western Canada.

However, official information is sketchy. Oregon was today reporting no cases of the virus but agriculture officials said they were monitoring 18 horses who attended the National Cutting Horse Association Western National Championships in Ogden, Utah, at the centre of the outbreak.

Montana officials understand about 35 horses from the state attended, and owners are being asked to watch for signs of the disease.

In Nebraska, state officials have placed five horse properties in isolation because they had horses at the Ogden championships. There is no official word from Western Canada at this time on the suggestion it has been affected by the outbreak.

To date, agriculture authorities have confirmed two cases in Colorado, in horses that attended the Ogden event from April 29 to May 8. Six other horses were reported to be showing symptoms and, to date, two horses have been euthanised because of severe neurological symptoms.

Washington state has one confirmed case, in a horse at the veterinary teaching hospital at Washington State University. It had also attended the show, but was admitted to the hospital on unrelated matters.

Other states are monitoring the situation and have been urging horse owners to take precautions against the potentially deadly disease, including isolating horses that have been to the show and limited horse contacts and movement.

The National Cutting Horse Association said today: "While reported cases of the virus are currently in Western states, the interstate transport of infected horses could cause a much wider spread of the virus if we are not all very cautious at this time."

It said affiliate organisations and show producers in Montana, Oregon, Oklahoma, Texas, California, Wyoming, New Mexico, Washington and Nevada have cancelled previously scheduled shows for this weekend as a precaution.

"The association supports these decisions to cancel shows that were made in the best interest of horse health.

"While the association is at present not mandating cancellation of all shows nationwide scheduled for the weekend of May 20-22, we do strongly urge all show producers to consider the possible horse health risks of conducting an event this weekend."

It said many veterinarians were working on the EHV-1 issue, and it was hoped that information available next week on cases and their geographic spread would allow the association to make the best informed decisions for shows scheduled in the coming weeks, including AQHA/NCHA Weekend scheduled for June 3-5, 2011.


The Utah Department of Agriculture and Food is investigating and has warned of the possibility of cancelling horse events if the outbreak spreads.

"There have been several cases of the disease in horses from surrounding states that returned from the National Cutting Horse Association's Western National Championships," state veterinarian Bruce King said.

"This highly contagious disease which spreads rapidly can result in the death of the animal. If horses become infected with this disease that were not at the NCHA in Ogden, I will recommend at that time that all events involving horses, mules and burros be cancelled in Utah.

Horses, he said, will still be allowed to travel in and out of the state, but he urged horse owners to call the destination state before travel.

King noted that equine university hospitals at Washington State University in Pullman and at Colorado State University, in Fort Collins, were under quarantines - the latter as a precautionary measure.

"This disease appears to be highly infectious and has resulted in numerous secondary cases," King said.

Symptoms include fever, decreased coordination, nasal discharge, urine dribbling, loss of tail tone, hind limb weakness, leaning against a wall or fence to maintain balance, lethargy, and the inability to rise.

While there is no cure, the symptoms of the disease may be treatable. Horse owners should watch their horses carefully and call their veterinarian if any abnormal signs are observed.


In Colorado, the agriculture department has implemented new travel requirements for horses entering the state.

"We are considering all of our options for protecting Colorado's horse industry," said state veterinarian Keith Roehr.

"At this point, we do not believe it's necessary to stop horses from entering the state but we need to be able to know where those horses are coming from and where they are going; traceback is a vital part of disease control," he said.

Standard requirements for horses entering Colorado include a health issued certificate within 30 days of their arrival and a negative Coggins test within 12 months.

The new requirement consists of a permit to enter the state. More details are below.


Case of EHV-1 in southern Alberta



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