Herpes Marches Through Maryland
Event Facility, Fair Hill Hit
At press time, the outbreak of equine herpesvirus (EHV-1, or "rhino") that began Jan. 2 and claimed the lives of four Maryland racehorses appears to be on the wane at local tracks. Since late January, however, two event horses at a private farm near Worton, on the Eastern Shore, have been euthanized due to the virus.
|Beyond the Racetrack
But elsewhere, EHV-1 still seems a clear and present danger. Two of the virus' most recent casualties occurred at the property formerly known as Seven Hills Farm, a boarding and training facility near Worton operated by noted event rider/trainer Kim Meier-Morani.
On Jan. 10, Meier-Morani received a yearling filly that came from the Ocala, Florida sales - by way of Pimlico - to be broken. At the time of the filly's layover at Pimlico, officials believed that the herpes virus was limited to the opposite side of the track, and traffic to and from Pimlico was still permitted.
Five days after the filly arrived at the farm, Meier-Morani says she got "the snots." But since she wasn't running a temperature, the horsewoman says she wasn't particularly concerned. In addition, she says that all of her horses are vaccinated against flu/rhino three times a year (in February, May and August, during peak travel times). "If you don't know what [the neurological form of the virus] does, you're not particularly worried about it, because you figure 'Hey, I gave a shot against it, I'm okay,'" she says.
Then, on Jan. 19, Meier-Morani received word that a horse in Pimlico's Barn A - the barn in which her new arrival had stayed - had tested positive for the virus. Although the outbreak had been featured in news reports around the state, Meier-Morani says she was unaware of it until that night. The next day, she had six horses with temperatures, three of them high.
Hohenhaus, who placed a Hold Order on the Meier-Morani farm on Jan. 26, says that the situation there isn't as easy to manage as individual racetrack barns, where horses are stallbound most of the time. "The horses [at the Worton farm] are commingled a large number of hours a day in pens and paddocks, and have fenceline contact," he explains. "So while there are two separate barns, there aren't two separate populations of horses, from a disease control standpoint. We had no choice but to consider all of them as exposed."
Since her experience with EHV-1 began, Meier-Morani says she's learned that although there are conflicting schools of thought on the efficacy (and even the advisability) of repeat vaccinations on the virus' neurologic form, many vets recommend that the flu/ rhino vaccine be given every 90 days - i.e., four times a year. She has also learned firsthand about the devastation the neurologic form can cause, having nursed two cherished homebreds - full sisters, in fact - through the heart-wrenching final hours of their lives. One was her daughter's 5-year-old Pony Club mount Just Testing, who was euthanized Jan. 26. The other, Test Pattern, was a 7-year-old Preliminary eventer and consistent ribbon winner who belonged to Meier- Morani's friend Susan Newton-Rhodes. She was euthanized Feb. 5.
At press time, Hohenhaus says the Worton farm has been infection-free (by the MDA's definition of that term) for about 10 days. However, Meier-Morani was still monitoring two horses impacted by the virus: the homebred Test Ride and her full sibling, Meier-Morani's beloved upper-level event horse Test Run. Tenth at the 2004 Rolex Kentucky CCI****, he also completed the 2004 Burghley CCI**** with Meier-Morani in the irons. "I have a four-star horse it took me my whole life to breed and develop," she says. "And he can't trot now."
Minimizing the Risk
At press time, Hohenhaus says officials were still trying to determine the status of interstate health papers on the filly from Florida that ended up at Meier-Morani's farm. The filly has reportedly recovered from the virus.
Did she pick up EHV-1 in Florida, at Pimlico, or somewhere in between? "It's hard to say," he admits. "[Florida officials] are telling our folks that they haven't had any problems anywhere. So is it possible that an 18-hour trailer ride caused herpes to emerge in that horse, and then it dropped off a present at Barn A on the way through? That's certainly possible."
As Hohenhaus explains, EHV-1 - which isn't as contagious as, say, influenza - lies dormant in many horses until activated by unknown triggers (some experts believe stress might play a role). "Why exactly it wakes up in that vicious form is not at all understood," he says. "I've always had at least a partial suspicion that the Barn A outbreak was separate and distinct from what was going on at the other side of Pimlico. It could just as easily be directly linked, but the circumstances suggest that it might be ... an unfortunate coincidence in time.
"But when the dust settles and the herpes season is behind us in a couple of months, [Gluck Equine Research Center in] Kentucky is going to attempt to do more detailed fingerprinting of the samples that we've sent them," he continues. "That allows us to compare viral types between barns and between individual horses."
Meanwhile, Hohenhaus says that while the current flu/rhino vaccine is no panacea, it's still best to administer it every 90-120 days. Some experts believe that routine vaccination might reduce the respiratory form of EHV-1 infection, which in turn might help prevent the neurologic form.
In terms of general hygiene, Hohenhaus recommends avoiding shared tack and handling, "particularly anything that has to do with the front of the horse, including the handlers' hands, bits and bridles, and identifiers at the tracks."
In addition, he says, "If the horse doesn't need to go somewhere, don't take him. On the other hand, if you have strange entries to your population, you really need to segregate them for, ideally, 21 days. But even a week is a huge benefit ... and that's just basic good husbandry.
"But you can't get the risk to zero," he emphasizes. "You have to accept the fact that if you're going to do with your horse what you would like to do with it - whether it's race it, ride it or show it - you're going to have to accept some risk."
© The Equiery 2010