Electron micrograph of EHV-1.
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.
* If you are the owner or trainer of a horse that has exhibited neurological symptoms of EHV-1, had a fever without neurological signs of the virus, or that has died from what you believe to be EHV-1, please contact the NCHA office by calling Pam Robison at 817/244-6188, ext. #111, or by e-mail at firstname.lastname@example.org.
* Horse owners who wish to bring their horse into Colorado must first call their veterinarian. That veterinarian can then contact the Colorado Department of Agriculture's State Veterinarian's Office at (303) 239-4161 and request a permit number. That number would then be included on the health certificate.
Additional Travel Tips for Horse Owners Traveling To or From Colorado:
Consider the disease risk before transporting horses.
Contact the State Veterinarian's Office of the destination state to find out if travel requirements have changed for that state.
Call organizers of the event to see if they have new health requirements or if it has been cancelled.
If traveling, practice appropriate biosecurity measures. Biosecurity tips may be found at www.colorado.gov/ag.
Isolate any new animals and those returning to the home premises for three weeks when possible.
Use separate water, feed supplies and equipment.
Continue to monitor the CDA webpage for further information to aid in the decision making for transporting horses.
If your horse attended the Ogden, Utah event:
CDA encourages all horse owners who attended the Ogden, UT, event should notify their veterinarian and isolate and monitor their horses for clinical signs of the disease. These horses should have their temperature taken twice a day. Horses with elevated temperature can be sampled by a veterinarian to analyze whether their horse is shedding EHV-1. Individual horse and barn bio-security is very important. Some horses may not show signs of the disease but may still be a carrier. Those owners are also encouraged to restrict movement of their horses.
General Disease Information
EHV-1 is not transmissible to people; it can be a serious equine disease that can cause respiratory, neurologic disease and death. The most common way for EHV-1 to spread is by direct horse-to-horse contact. It can also be spread by contaminated tack, equipment, and people's clothing. In addition, the virus can be spread through aerosols (airborne) for a limited distance.
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 isolate any sick horses and immediately contact their veterinarian. Any individual horse with clinical signs consistent with neurological EHV-1 infection should be removed immediately from the area and placed in a separate enclosure for isolation.