EHV Linked to Cutting Horse Event, Multiple Western US States Alerted for Disease After Two Horses Euthanized

Update Sunday May 15: From Sally Harrison’s blog: “In a precautionary move to ensure the health and safety of horses, the Breeder’s Invitational board of directors has canceled their Breeder’s Invitational cutting event in Tulsa, Okla., from May 14-28, and the National Cutting Horse Association has also cancelled the Mercuria World Series of Cutting this weekend in Tulsa.” For more information, read Sally Harrison’s Blog. Sally is my go-to source for information on the sport of cutting.

On its Facebook page, the NCHA reported on Sunday that sick cutting horses had been reported in several western states and in western Canada, but that the only confirmed diagnosis of EHV-1 had been in the Colorado horses via Colorado State University.

I received a Facebook message on Friday morning from a farrier in Colorado who was concerned about having worked on a horse that was believed to be ill with the neurologic form of Equine Herpes Virus (EHV). A second horse at the farm had been euthanized and the diagnosis of EHV had been confirmed by the laboratory at Colorado State University. The farm had been quarantined according to the farrier, who was conscientiously concerned about spreading the disease to other horses at other farms.

Checking with disease outbreak alerts, I couldn’t see any for Colorado, so I contacted the State Veterinarian’s office there on Friday; a representative told me that not just one, but two farms in Colorado’s Weld County, had been quarantined and the diagnosis had been the neurologic form of EHV. She said the state would issue a press release on Monday.

I sent a warning out via Twitter that EHV had been diagnosed in Colorado and more details would be forthcoming.

The vet’s office must have received a lot of calls, because a press release appeared on the Internet on Saturday afternoon.

The release confirmed the facts that I had. “The Department is taking quick and appropriate actions to control and mitigate this disease,” said State Veterinarian Dr. Keith Roehr in the release.  “We will continue to trace the movement of these horses and those horses they came into contact with in order to protect Colorado’s equine industry.”

Both diagnosed horses had recently attended the National Cutting Horse Association’s Western National Championships in Ogden, Utah.  The Colorado Department of Agriculture is working with the Utah State Veterinarian to investigate the location as a point of interest for the infection.

This morning, Quarter Horse News posted an article suggesting that the source of the Colorado disease was the Utah event.

In addition, Quarter Horse News reported that “At the Kern County cutting in California on May 13, one horse allegedly died of the disease and another was rushed to University of California, Davis, according to one cutting horse person present at the event. The show was immediately canceled.”

NCHA Announcement

An announcement on the National Cutting Horse Association web site alerts exhibitors from the Ogden event to be aware that two horses have tested positive for EHV.

Information from the announcement includes: “While we do not wish to unnecessarily alarm you, we wanted to get this information to you as soon as we received it. If you had a horse competing at the NCHA Western National Championships in Ogden, you may wish to consult with your local veterinarian on this issue. Any symptoms reportedly typically show within 4 – 6 days of exposure to the virus, and initially are in the form of a fever in the affected animal.”

California Update

This afternoon I interviewed Peggy Biller, president of the Kern County Cutting Horse Association in California, who verified the basic facts that had been reported by Quarter Horse News. She said that her organization had planned a three-day cutting for this weekend. The event began on Friday as scheduled. However, a horse was euthanized on the grounds and another horse became ill. Both horses had been at the NCHA event in Utah. The body of the dead horse was transported to the state laboratory in Tulare, California. The second horse was transported to the equine hospital at the University of California at Davis.

“People basically panicked,” Biller said. “They just wanted to get their horses out of there.” She said that there was a mixture of horses that had and had not been at the Utah event present at her event. She didn’t want to comment about how long the majority of horses had been on the grounds and already exposed to horses that had been in Utah or the sick horses themselves.

I was reminded of the shutdown of an Australian three-day event during the Equine Influenza outbreak there. When horses started to show signs of illness, no horses were allowed to leave the showground and were forced into a lock-down quarantine for three weeks rather than allow them to return to their home farms and possibly spread disease to more horses.

“Everybody panicked and ran,” said John Ward, vice-president of the Kern County Cutting Horse Association on the telephone today. “You’d have thought there was an earthquake. It was just like someone yelled, ‘Fire’!” Ward said that he felt very sorry for the owner of the two sick horses.

Ward commented that he thought people would follow the advice of veterinarians to monitor the horses’ temperatures twice a day. “These horses are worth a fortune,” he said. “And in the future, they will pay much closer attention when a horse acts different or is lethargic.”

A little web investigation revealed a memo dated both May 8 and May 13 that had gone out to California-based cutting horse exhibitors who had been at the Utah event. The memo was signed by Kent Fowler, DVM, Animal Health Branch Chief of the California Department of Food and Agriculture. The memo is posted on the California  Department of Food and Agriculture web site, if one knows that there is an EHV information page about six clicks deep into the site. There is no mention of EHV on the animal health main page, although there are alerts about bovine tuberculosis, Newcastle disease in Mexico and other disease outbreaks.

Among other things, the memo warned, “The California Department of Food and Agriculture encourages owners of horses who participated in the Odgen, Utah event to isolate and monitor their horses for clinical signs of disease.  A rectal temperature in excess of 102F commonly precedes other clinical signs.  Therefore, we are urging owners to take temperatures on each individual horse(s) twice a day.  If a temperature above 102F is detected contact your private practitioner immediately.  Laboratory submission of nasal swabs and blood samples collected from the exposed horse can be utilized for virus detection and isolation.”

Elsewhere in California, the Pacific Coast Cutting Horse Association announced the cancellation of the May 15 Clements Cutting Club Cutting and the PCCHA Tejon Ranch Cutting, May 19-22.

Commentary from The Equid Blog

Drs Scott Weese and Maureen Anderson , authors of the Equid Blog, from the Ontario Veterinary College at the University of Guelph in Canada, were monitoring the situation today and offered a sage summary of the week’s events.

“Whether or not the show is where the horses were first infected is unclear, but it makes sense because any time you mix together large numbers of horses, and stress them through shipping, competition, management changes and other factors, infectious disease exposure risks rise. This may be particularly true for EHV-1, since the virus is lying dormant within a large percentage of healthy horses. Most of the time, infected horses are not shedding the virus, but shedding can occur if horses are stressed or sick.

“EHV outbreaks and quarantines seem to be much more commonly reported over the past couple of years. Whether that’s because of a true increase in disease or an increase in publicity and response to disease is unclear. There has been a big change in our understanding of how EHV-1 “works,” through identification of a mutation in some strains that makes them more likely to cause neurological disease (and outbreaks).

“Tests are now available for this mutation, and this strain may be increasingly common. However, this strain doesn’t always cause neurological disease, and strains without the mutation can still cause neurological disease, so it’s not a completely clear situation. I suspect that we are truly seeing some increase in disease, but we are seeing an equal (or greater) increase in response to single cases or small outbreaks, with quarantines and press releases that would have been rare not too long ago.

“EHV-1 is all over the place and complete avoidance of it is impossible. Good general infection control practices to limit the spread of the virus when it is being shed by horses, and prompt identification and isolation of horses with EHV infection are important but often overlooked control measures.”

Type in red is quoted from the Equid Blog. Both Dr Weese and Dr Anderson are large animal internal medicine specialists with expertise in infectious diseases and infection control. Their blog is an excellent source of equine health information.

To learn more about the neurologic form of EHV, download the USDA brochure, Equine Herpesvirus Myeloencephalopathy.

And keep reading this blog. We’ll do our best to find out about equine public health situations and provide information with sources listed. Even if these alerts do not affect you directly, you can learn about these diseases and how to prevent them in your own horses.

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