Few reports instill more panic than those that include words such as “mutant virus,” “highly contagious,” and “death.”

The equine herpes neurologic virus outbreak in Florida and elsewhere around the country this winter has shown that horse people are no different. Generally known for their level-headedness in situations involving blood and breaks, riders, owners and trainers have suddenly encountered a virulent, fear-inducing neurological form of a virus that they can’t see and can’t, with total certainty, prevent.

Desperate for reliable information, many horse people turned to a source more trusted than even the latest-breaking online news: their veterinarians.

From Maryland to the Midwest, Florida to California, clinicians have ramped up efforts to contain the disease where outbreaks have occurred and soothed fears where it hasn’t. All have been taxed with explaining the virus’ many forms—which can range from a mild respir-atory infection to a potentially fatal infection of the nervous system—and recommending precautionary measures.

In Wellington and Ocala, Fla., where seasonal traffic is at its peak, controlling the virus, and the public’s reaction to it, has been an even greater challenge. While it looks as though the Wellington horse shows stand poised to sound the all-clear on Jan. 19, veterinarians are still stumped as to the origin of the new strain of herpes. Meanwhile, they’re helping owners figure out the best prevention measures to adopt now that the peak period for new infections appears to have passed.

“People want to know if you test for this, but the techniques to find it in advance are basically none,” said Paul Lunn, head of the Department of Clinical Sciences at Colorado State University’s College of Veterinary Medicine, and a specialist in herpes virology.

Although the disease has been around for decades and commonly flares up on racetracks in its more common respiratory form, the more serious neurological form of the virus has stumped Lunn and other researchers since an outbreak at University of Findlay (Ohio) in 2003 killed 12 horses.

“If you’re a horse, you’re going to get herpes,” Lunn said matter-of-factly. “Having herpes is part of being a mammal. In most horses’ first few days of life, they are exposed to the virus and then carry it for life, though usually it just quietly sits there. When horses get stressed, it can break out, but what we don’t fully understand is what predisposes horses to this neurological form of the disease.”

Quelling Rumors

Currently, the two forms of herpes most veterinarians vaccinate against are the respiratory and abortogenic forms of the virus. The former routinely occurs in young horses and results in some coughing, a snotty nose and a loss of appetite before the animals recover in a few days. Pregnant mares that become infected often end up aborting their foals late in gestation or delivering a foal that dies a short time later.

Until recently, it was rare that a horse would develop respiratory herpes and then develop the neurological form of the disease, which produces symptoms such as loss of coordination, lower leg swelling, urine dribbling, and eventually, the inability to stand. In these cases, horses usually have a low-grade fever that goes away, only to be replaced by a high-grade fever.

One of 15 horses imported from Europe in November and quarantined in New York was euthanized after being shipped to California, where it showed progressive neurological symptoms in early December and eventually tested positive for EHV-1. Meanwhile, five horses in that same group were shipped to Wellington on Nov. 29, said Lisa Hinder, a veterinarian with the Equine Medical Center of Ocala. This set in motion a chain of contact that resulted in the state quarantining barns in Ocala, Wellington and Indiantown, Fla.

According to the state of Florida as of press time, 13 horses have been infected, seven of which showed neurological signs. Six deaths have been associated with the virus, including Debbie Stephens’ grand prix jumper, Cosequin’s CEO, who was one of the first Florida-based horses to die on Dec. 10 of a then unknown illness.

Hinder remembered the horse community “freaking out” in December before a public meeting was called in Ocala on Dec. 20.

“Rumors flew,” Hinder said. “Things like Florida being closed down–you should have heard the rumors: ‘They’re closing the borders to Florida,’ ‘You can only use such-and-such vaccine,’ ‘As many as 30 to 40 horses have died.’ “

For almost a week, Hinder spent between three to four hours on the phone each day with worried clients.

On Dec. 20, veterinarians representing the state Department of Agriculture addressed dozens of people at the Ocala Breeders’ Sales Company’s auction auditorium. There, Hinder said, state veterinarian Michael Short explained how an exposed horse from Wellington had been transported to Calder Racetrack, which seemed to have allowed the virus to spread to a horse that was transported to Tuxedo Farm in Ocala.

“Short was totally honest with people,” Hinder said, “and he explained how we didn’t have vaccination histories on all the horses that had come through, and he also named which farms had suspect cases.”

After the public meeting, Short led a closed-door discussion with about 40 veterinarians in the Ocala area about how to handle the crisis. The clinicians talked about suspicious cases, what signs to look for, the pros and cons of herpes vaccinations and how to know whether to call the state department if a horse spiked a fever.

“The consensus was to still use our best judgment,” Hinder said. “The state made it clear they couldn’t handle everyone calling them for every horse we found with a fever.”

Less than a week earlier on Dec. 14, a similar public discussion and veterinarian’s meeting was held in Wellington, said Bill Patterson, an Ohio-based veterinarian who treats horses in Palm Beach over the winter.

“The community was kind of blind-sided by this, but the veterinarians came together and tried to figure out the best way to contain it,” said Patterson, who was one of about 60 area veterinarians who attended the Wellington meeting.

“First we talked about viral security measures and how to establish quarantine boundaries. We reviewed the protocol for testing: when does it start? Where was the first case? How did this thing progress? As a group, we decided that vaccination would be helpful to reduce the shedding of the virus, though it was unlikely to prevent the disease. And, of course, the other big concern was what this meant for the horse show schedule.”

In an ambitious risk-management measure, the state and local veterinarians agreed to encourage new people not to come to Florida until after Christmas, Patterson added.

“My phone traffic was crazy,” he said, remembering the pre-Christmas frenzy last month. “But it looks like by the 19th of January we’ll be ready to test the all-clear.”

Vigilance Is Good

But lingering fear of a virus outbreak, EHV-1 or otherwise, is unlikely to subside any time soon. In fact, many veterinarians hope it won’t. According to Lunn at Colorado State, owners have been lulled into a false sense of security for years considering how often our horses travel—internationally, state to state, show barn to horse show—and mingle with other horses potentially infected with something along the way.

“We treat them like we treat ourselves,” said Lunn. “We demand that we have the facilities completely full, that we walk wherever we want, exercise whenever we want. Yet just 300 years ago with humans, such congregations like that would have been a catastrophe. Just imagine that at a time with no vaccine for smallpox.”

Now more than ever, bio-security is presenting a huge challenge to event organizers and show managers, Lunn added, because by the time someone identifies the first sick horse, it’s already too late. With travel habits unlikely to change, however, Lunn and other veterinarians across the country are stressing the importance of quarantine areas at barns where horses come and go frequently.

“I’ve often been critical of this—when horses get sick in big barns, you should have a place away from the other horses where you can move them to,” said Don Walsh, a veterinarian in St. Louis, Mo. Although no positive cases have been identified in Missouri, seven horses at a Lake St. Louis hunter/jumper show at the National Equestrian Center had to be quarantined last month when it was discovered that they had been shipped for three hours with the horse who eventually tested positive for EHV-1 and died in California.

“The trainer did the responsible thing when the vet from California called him and said it looked like the horse there was deteriorating,” said Burny Baxter, who runs Mid-Rivers Equine Centre in Wentzville, Mo., and handled the case. “We isolated the horses at Lake St. Louis, contacted the state vet’s office and monitored the horses’ temperatures here four times a day for about three weeks straight.”

Baxter said they were careful to use the same pitchfork to clean each stall, and to assign personal grooms to each horse.

In the end, nasal swabs of each horse and an examination of the buffy coat (or white blood cell samples) all came back negative for EHV-1.

Still Many Questions

Yet the increasing numbers of neurological herpes virus cases raises other concerns—such as the infection’s mysterious origins–that can’t all be alleviated by following strict quarantine protocol.

Some veterinarians have suggested the recent neurological cases must be linked to a mutant strain of the herpes virus, but Lunn said that can’t be supported yet with scientific evidence, and there’s still a chance that the cases could be a cyclical occurrence.

Even more perplexing, Lunn said, is that a team of researchers in 2003 or 2004 supplied evidence that a mutation might have occurred in the herpes gene, but that it was unclear whether that mutation occurred recently or a century ago. What nobody can answer is that if it’s not a “new” strain of the herpes virus gene, then why are so many horses suddenly coming down with symptoms, and why has it afflicted those equines in particular and remained dormant in others? And of the horses that show symptoms, why are some able to make a complete recovery while others seem destined to succumb to severe ataxia?

Prevention through vaccination is another issue. Unfortunately, herpes virus vaccines are far less effective than a tetanus or West Nile vaccine, though a recent study of herpes “modified-live” virus vaccine did prove in a small sample of horses to offer more resistance to the neurological strain of the virus than the more typically administered “kill vaccine.”

Currently, Pfizer is pushing the relabeled modified-live virus vaccine (Lunn said it’s been around for 20 or 30 years, but that Pfizer is the latest company to market it). The vaccine is more expensive and comes with a greater risk of reaction to the shot, but most veterinarians seem to be recommending that show horses and other equines that travel frequently receive the live-modified product.

Skeptics, however, may worry that increased use of the modified-live virus vaccine could increase the potential for a bad batch of the material to actually cause the virus. Lunn said that currently, there’s no evidence to substantiate that concern.

Florida Lawsuit Heats Up

As the fervor over containing a virus begins to wind down in Florida, a lawsuit about the handling of the case by the state, and the privacy of veterinary record, is just beginning.

On Jan. 3, the prominent Palm Beach Equine Clinic in Wellington, Fla., filed a lawsuit against the Florida Department of Agriculture, claiming that the state’s chief veterinarian and media spokesperson hurt the clinic’s business when they falsely claimed that a horse with EHV-1 died at the clinic, and that the facility was under a state-mandated quarantine.

In reality, said prosecuting attorney Craig Galle, it was the nearby Palm Beach Equine Sports Complex that had the sick horse and the mandated quarantine.

“The state kept making this mistake over and over during a two-week period, and as a result, my clients’ monthly revenue for December was down by 40 percent from November,” Galle said. “The false release of information meant our clients were worried, and we believe many of them were not calling on our veterinarians to come service their horses because of it.”

According to the official complaint, on Dec. 2-3, Palm Beach Equine Clinic did house one of the EHV-1 infected horses that was shipped from New York, but nobody made the connection to the outbreak until Dec. 15. Testing on that day revealed the hospital itself was free of EHV-1.

Yet the lawsuit also calls into question the privacy of medical records for horses. According to the complaint filed by the plaintiffs, state veterinarian Thomas Holt and spokesperson Mark Fagan released “non-public, private veterinary medical information about PBEC’s clients without the consent of either PBEC or its clients.”

Galle said that while the state could release which facilities are under state-mandated quarantine, it was not right for officials to release names of the horses who were sick, or likewise, the names of the people who owned those horses.

In response, attorney Chris Whitelock, the legal representation for Florida, called the lawsuit, “without merit and frivolous.”

“Quarantine orders and direct communication were for the health of the horses and for others so this disease didn’t spread,” Whitelock said. “The only thing my clients did intentionally was to make sure these horses and others were safe.”

As for the alleged defamation claim, Whitelock explained that it was a prominent local newspaper that mixed up the names of the equine clinics, not state employees. He added that it was an admitted error by the publisher, which was further supported by a retraction in print.

Whitelock said he doesn’t anticipate this case going to trial, and that the plaintiffs have not even identified how much they are seeking in damages over the minimum $15,000 needed to file a case. In response, Galle said his clients are waiting to name that fee until they assess losses at the business for January, February and March.

Some Basic Herpes Facts Detection

The first sign of a herpes infection, like many other infections, is often a low-grade fever. In the neurologic form of EHV-1, said Mark Cassells, a veterinarian with Homestead Equine Hospital in St. Louis, Mo., the low-grade fever often goes away and then comes back as a high-grade fever.

If you think your horse is developing symptoms, or if you think it might have come into contact with a horse that has, standard procedure involves taking the equine’s temperature four times a day, or every six hours (remember that normal body temperature is about 100.5 degrees Fahrenheit). If the horse’s fever persists, isolate the animal and call the veterinarian. He or she will probably take a nasal swab and a sample of the horse’s white blood cells for laboratory testing.

If your horse tests positive for EHV-1, limit the number of people coming into the barn and institute foot baths to disinfect outer footwear at the doors of the barn. Employees should wash their hands with soap and water after handling each horse. The virus is only alive in the outside environment for two to three hours, but it can be carried on your clothing to another animal. Minimize the use of shared equipment like brushes and even pitchforks, and don’t let items like feed scoops contact the horse’s bucket or trough. In many cases, a horse can make a full recovery from even the neurologic EHV-1 strain, provided it remains standing. Horses who lose the ability to stand have a much lower rate of recovery.

Treatment

Unfortunately, there is no drug that can “cure” a herpes virus outbreak. Veterinarian Burny Baxter from Mid-Rivers Equine in Wentzville, Mo., said the human anti-herpes medication Valtrex (valacyclovir) has shown some efficacy, and that high doses of Vitamin C have also been helpful. Baxter also said 5 to 10 grams of the amino acid lysine can be effective. Anti-inflammatory drugs are commonly administered, and fluids can help to maintain the animal’s hydration.

Prevention

Although herpes cannot be prevented completely, normal flu-rhino vaccines protect against the respiratory and abortogenic strains of the virus. The modified-live virus “rhinomune” vaccine currently marketed by Pfizer has shown some added resistance to the neurologic strain of the virus, and most veterinarians have recommended it for horses that are on the move a lot, or who live in barns where stablemates come and go frequently. The traditional “killed vaccine” and the “modified-live vaccine” can be used in conjunction.