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UW-RF expert: Awareness, fast response helped contain deadly horse virus

UW-River Falls Animal Health Professor Peter Rayne is shown with Tonka at the university’s Campus Laboratory Farm. (River Falls Journal photo by Chuck Nowlen)

An outbreak of the potentially deadly Equine Herpes Virus threw a scare into the local horse community early this year but was contained by quick action on well-established response protocols, according to a UW-River Falls expert.

“It’s one of those things where you have to be ever-vigilant,” Animal Health Professor Peter Rayne said in an interview last week.

“So there was a lot of interest and awareness once the initial cases were diagnosed… There have been no cases in the state since late March, when the last positive horse was identified in Wisconsin.”

At least 10 horses were infected with Equine Herpes Virus in Wisconsin, Minnesota and Iowa in March and April.

This included one horse in St. Croix County and two others in Polk and Lafayette counties, according to several reports. One report also listed an infection in Burnett County.

A second, “highly suspicious” case occurred in St. Croix County in February. That animal was euthanized, according to another source.

The case reportedly involved the same farm where Equine Herpes Virus was later confirmed in March.

The highly contagious virus, which remains dormant in infected animals after exposure but can revive during periods of stress, can cause neurological, urinary and respiratory problems, neonatal death and abortion.

The virus is spread by horse-to-horse contact but also through tack, grooming equipment or feed and water buckets, for example. It is not harmful to humans but can be passed to horses by people’s hands or clothing.

Rayne noted that there are two strains of Equine Herpes Virus, or EHV-1: the deadly Strain D, which “has a very high propensity to create neurological problems;” and a milder Strain E, which “is not as virulent but still can cause problems.”

Strain D was not confirmed in any of the Wisconsin cases, he said.

Rayne added that horses can be especially vulnerable to EHV-1 in the spring and fall due to seasonal weather changes and transportation stress when they are taken to industry shows and exhibitions, for example.

“It’s a herpes virus, and one characteristic of that virus is that once an animal is infected, the virus becomes latent, and then, during a period of stress, it can come out again,” he said. “At that point, the animal will shed the virus, so it can be transmitted through nose-to-nose contact and through other means.”

Typically, the onset of EHV-1 is marked by a mild fever that goes away after four or five days, followed by a more prolonged fever and symptoms that tend to appear eight to 10 days later. EHV-1 can be positively diagnosed via a nasal swab and a detection test.

“The key is early detection and treatment,” Rayne explained.

Follow-up treatment includes quarantine and restricted movement, anti-inflammatory drugs and general supportive care. In cases where neurological problems are present, animals may have to be kept in padded stalls and special slings may have to be used to help them stand.

Rayne credited widespread awareness of the disease’s potential, effective industry-wide communication -- now boosted by social media -- and established treatment and prevention protocols with keeping the 2014 outbreak from getting out of hand.

For the complete story, please see the July 17 print edition of the River Falls Journal.

Chuck Nowlen

Chuck Nowlen joined the Star-Observer team as a business, township and general-assignment reporter in April, 2014 after a three-decade career in newspapers and magazines, and as a newsroom-management/business-planning consultant.

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