Horse Health Reminder: EHV Infection Risk Rises in Colder Weather

by Fran Jurga | 13 October 2009 | The Jurga Report at Equisearch.com

As the thermometer dives, the whole horse world's outlook changes. Everyone goes looking for clipper blades that aren't rusty. They want their blankets mended...by next week. That hay order had better get here quick. And where are my gloves?

While most barns are very responsible about scheduling fall shots and checking into winter nutritional programs for horses coming off grass, there's a little something to keep in the back of your mind. Something that has no vaccine but is a real risk to your horse.

This is the time of the year when horses are in heavy transit. There's the mass migration to Florida (those lucky people and horses) and there are hundreds or even thousands of horses on the roads to and from Oklahoma for the year-end shows.

The most telltale sign of herpes virus is thick, yellow mucus. Do you have a plan to be able to isolate a sick horse from the other animals who share his stable or pasture?

It's a simple equation: horses in motion + cold weather = risk of disease. And one that a vaccination won't cover is the neurological form of Equine Herpes, which is now known as Equine herpesvirus myeloencephalopathy (EHM). There are actually nine forms of Equine Herpes, but people are usually concerned with three forms. EHM is a mutant strain of EHV-1.

The Wisconsin State Veterinarian, Dr. Robert Ehlenfeldt, has issued a special warning to horse owners in that northern state, but it makes plenty of sense, so I thought I would pass some of his points on to you so you could do what you can to protect your horse.

Equine herpes virus type 1, or EHV-1, usually causes a respiratory infection called rhino-pneumonitis. But it also has a more serious, often fatal, neurologic form that strikes the horse's central nervous system.

A recent study by researchers at the University of Kentucky found that the neurologic form is increasingly prevalent. Historically, they found that only about three percent of EHV-1 cases were neurologic in the 1960s. But in the 1990s, over 14 percent were neurologic, and by 2006, more than 19 percent of EHV-1 cases were the more dangerous strain.

Staggering, standing with splayed legs and general incoordination are typical of the neurological form of Equine Herpes.

In 2006 an outbreak of this strain of the disease arrived in the United States with a shipment of horses from Germany; the horses scattered to eight states.

"Like a lot of viruses, this one thrives in cooler conditions, so we're coming into EHV season," Ehlenfeldt said. "There's no vaccine for this form of the disease, so biosecurity is even more important."

EHV-1 spreads when horses in close contact cough or sneeze, and on contaminated hands, water and feed. It can cause abortion in pregnant mares and death in foals. The neurologic strain may cause horses to be uncoordinated, unable to stand, and unable to eliminate urine and manure. They may also have swollen, inflamed legs and hemorrhages on their gums. EHV-1 vaccines are not effective against the neurologic form.

Some horses do stand with crossed legs while on cross-tied, but it is not normal for most horses in general stance. EHV's neurological form may make it seem like the horse isn't sure where his feet are.

Watch this blog for news about EHV outbreaks in different parts of the country (or notify me if you hear of one).

Special for readers for The Jurga Report: The USDA has pubished a special report for 2009, called Equine Herpes Virus (EHV) Myeloencephalopathy: A Guide to Understanding the Neurologic Form of EHV Infection. Click here to begin the download.

I thought this brochure was really helpful, and up to date. I hope you never need it, but if you have a horse on your property with any suspicious symptoms, this brochure will be very useful to have. You can print it out or store it on your computer. The photos accompanying this blog post are a few you will find in the USDA brochure.

Equine Herpesvirus Confirmed in Oklahoma; Biosecurity Stressed For Horse Owners

(public service announcement for horse owners)

Oklahoma City—State Veterinarian, Becky Brewer, confirmed today that a state horse has tested positive for Equine Herpesvirus-1 (EHV-1) and has been placed under quarantine. Further tests are being conducted to determine if this is a relatively new strain of virus.

“EHV is a very common equine virus and until recently was more easily controlled with biosecurity measures and a good vaccination program,” Brewer said. “The virus has undergone a genetic mutation that can infect even vaccinated horses.”

The new strain has a high mortality rate as opposed to the more common forms of EHV, she adds.

“We must stress that we don’t yet know if this is in fact the new EHV-1 virus,” Brewer said. “Samples have been sent to a laboratory in California for final confirmation and we will have the results some time next week.”

EHV-1 is a respiratory disease and may be spread through the air, on tack, horse trailers and other forms of direct or indirect contact. Anyone contacting horses should change clothes, disinfect boots or shoes and wash their hands with soap and water before having contact with horses at another facility.

“Vaccination and biosecurity are our best methods of dealing with this disease and we are urging horse owners to take this issue seriously,” Brewer said.

An EHV fact sheet is available on the Oklahoma Department of Agriculture, Food, and Forestry website at http://www.oda.state.ok.us/ais.htm. Updates will also be posted on the agency’s blog at www.agblog.ok.gov.

ODAFF policy prevents the location of quarantined animals or the identification of their owners to be released unless necessary to protect the public.

EHV in Delaware: Small State Tackles Big Problem (Again)

Let's hope 2009 is a disease-free year for tiny Delaware. Last week two Standardbred horses were euthanized there after becoming ill and testing positive for Equine Herpes Virus (EHV-1). One horse was at Dovington Training Center and the other at Tana Merah Training Center.

According to a report released yesterday by the state's Department of Agriculture, both premises were inspected last week to ensure that biosecurity protocols are in place, and to review the temperature charts in each barn. Animals in the quarantined barns will continue to have body temperatures monitored every 12 hours for the duration of the quarantine period.

According to Dr. Heather Hirst, Delaware's State Veterinarian, no horses on the farms are showing clinical signs of EHV-1. "While the continued health of animals on both premises is promising, we are certainly not at a point where vigilance can be relaxed. We must maintain the highest level of biosecurity and observation for new cases in order to protect Delaware's equine population and our vital racing industry,” said Dr. Hirst.

Dr. Hirst continued, “I want to commend the practicing veterinarians of Delaware, the Delaware Veterinary Medical Association, the Delaware Equine Council, and Dover Downs for their efforts in providing open communication during the EHV event.”

Dr. Janice Sosnowski of Delmarva Equine Clinic organized two meetings in December with the help of Dover Downs management. The first meeting was for veterinarians and track officials, and Dr. Amy Johnson of New Bolton Center was invited to speak to the group about EHV-1.

The second meeting was for horsemen, and its intent was to describe best management practices for controlling the spread of EHV-1 in Delaware. Approximately 50 horsemen attended, and detailed handouts were provided describing biosecurity protocols.

Dover Downs, a harness racing track, has implemented new, stricter biosecurity measures to reduce the chance of spread of EHV-1 and other infectious organisms. These new policies include: disinfection of the starting gate after each race, regular disinfection of the receiving (ship in) stalls, and regular disinfection of the paddock.

“I have been truly impressed with the level of cooperation we’ve encountered among all members of the equine racing industry. This is not something we should take for granted,” said Dr. Hirst in the announcement.

While Delaware is a small state, the relative horse population is high. Horses regularly ship from and through and into Delaware from neighboring Maryland, Virginia, New Jersey and Pennsylvania. Standardbred racing and breeding stock are particularly mobile in the area.

Delaware began the year with a neurological herpes problem in January, when five farms in Kent County were quarantined after a horse was euthanized because of severe herpes symptoms.

Herpes at New Orleans Track; Biosecurity Increases as Racing Goes On at The Fair Grounds

The following information is provided by The Fair Grounds in New Orleans, Louisiana for the information of anyone in the state or who might be interested in this latest outbreak of EHV.

A barn in Fair Grounds' stable area is under a Louisiana State Racing Commission quarantine after test results confirmed that a horse in that barn was infected with equine herpes virus ("EHV1").

Officials with the LSRC have ordered biosecurity measures in place in Barns 4A and 4B, which are under the same roof and house horses trained by Dallas Stewart and Neil Howard. The quarantine of the barns was ordered after a Thoroughbred trained by Stewart displayed symptoms of equine herpes on Tuesday. That horse was transported immediately from Fair Grounds and is now under observation at Rood and Riddle Equine Hospital in Lexington, Kentucky, where the diagnosis was confirmed on Wednesday.

The quarantine order affects 44 horses in Stewart's section of the barn and 27 horses under Howard's care.

"The horse is doing well in Kentucky and starting to show some improvement," said Tom V. David, DVM, equine medical director for the LSRC. "We remain cautious because we still do not have enough information. Until we get more test results on the horses in that barn, we don't know the total extent."

Dr. David said the implementation of the quarantine and its associated biosecurity measures was ordered in an effort to contain and isolate any possible EHV1 cases to that barn and prevent any spread of the virus among the horse population at Fair Grounds.

Symptoms of equine herpes virus most commonly include fever and an upper respiratory infection. The symptoms can also include lethargy, loss of appetite, a nasal discharge and a cough. In severe cases, horses can suffer a loss of coordination and an inability to stand and the illness can be fatal.

The disease is a virus, so it can be spread through the air when a horse coughs - although studies on the virus indicate that it is very short-lived and is susceptible to disinfectants. The maximum extent of the airborne transmission of the virus is thought to 35 feet. Horses may also contract the disease if they come in contact with the clothing of a person who has worked with an infected horse, the tack and equipment worn by an infected horse, or a shared food and water source.

The recommended quarantine period is generally up to 21 days after potential exposure to the virus. The incubation period for the disease ranges from two to 10 days. Under the quarantine order, horses may not be moved in or out of those barns until state agriculture officials clear them to do so.

The quarantine is not expected to have a negative impact on Fair Grounds' season, which began November 14 and continues through March 29, as horses will continue to be permitted to ship in and out of the track to race.

To accommodate the quarantined horses, training hours have been changed. Horses from Stewart and Howard's stables will be allowed to train from 9:30-10:30 a.m.

Additional biosecurity measures have been put in place to guard against the introduction of the virus to the track's horse population. Those procedures include:

• Increased scrutiny of horses that arrive and depart from Fair Grounds' barn area, with certificates of veterinary inspection required for all horses that enter the stable area;
• A requirement that horses that ship in to compete be allowed only into the track's Receiving Barn;
• Nightly disinfectant procedures in the Receiving Barn;
• Daily disinfectant procedures on the starting gate;
• The track's horse identifier and starting gate crew will be required to use latex gloves and follow other recommended disinfectant procedures for their work areas, equipment and practices;
• And daily disinfectant procedures in the paddock following the conclusion of each day's racing.

Equine Herpes Virus at Maryland Racetrack: Filly Euthanized

A young Thoroughbred racehorse has been euthanized at Maryland's Laurel Park racetrack after showing signs and testing positive for the Equine Herpes virus (EHV). Officials curtailed horse traffic in and out of the racetrack last Friday when the sick filly was confirming to be infected with EHV.

It was just two years ago that an EHV outbreak on the South Florida showgrounds at Wellington threatened the hunter/jumper showing circuit; this is the second outbreak at a racetrack in the state of Maryland in recent years.

On Monday, Maryland Department of Agriculture (MDA) Animal Health staff took nasal swabs and blood samples from the 18 remaining untested horses in Barn 1, where the filly was tabled. Complete results received on Tuesday from the horses stabled in Barn 1 to date are all negative test results. In addition, samples from 31 lead ponies submitted by the Maryland Jockey Club on Saturday are all negative, as are tests on horses that had shipped out of the barn.

Equine herpes virus causes upper respiratory infection and can lead to severe neurological disease. There is currently no known method to reliably prevent the neurological form of EHV-1 infection. It is recommended to maintain appropriate vaccination procedures in an attempt to reduce the incidence of the respiratory form of EHV-1 infection, which may help prevent the neurological form. Transmission occurs primarily by direct nose to nose contact or contaminated hands, equipment, feed and water. It can also be spread up to 35 feet by airborne droplets. This virus is not associated with any human health risk.

Photo of bio-emergency drill courtesy of Maryland Department of Agriculture Animal Health Section.

Hurricane and Disease Worries Hit New York Racing with a One-Two Punch Today

Summer's over.

Thoroughbred racing in New York migrated back to Belmont Park near New York City on Friday, only to have Tropical Storm Hanna pelt the track with rain today. Sunny Saratoga seemed like distant memory. Slickers came out, and races went on, but talk turned to other threats as the storm headed up the coast toward Boston.

According to New York City news sources and the Daily Racing Form, a three-year-old gelding who shipped down from Saratoga earlier this week was euthanized today. The horse had a fever and was unable to stand.

The barn where the horse was stabled, which houses horses for several trainers, is now under quarantine and a laboratory in Kentucky is conducting tests to determine if the horse suffered from a contagious disease, such as Equine Herpes virus (EHV).

The dead horse had the clever name "Smell My Carrots". Test results are expected Tuesday. Other horses in the barn will not be allowed to race, train on the main track, or mingle with other horses.

Many of the top stakes horses in the country are stabled at Belmont for the rich fall stakes series, however several--including Breeders Cup winner Kip De Ville and veteran campaigner Better Talk Now--are currently in Toronto for a rich weekend of racing at Woodbine. A disease outbreak at Belmont could affect the shipment of such top horses to New York. Horses stabled at Saratoga for racing through Labor Day have now dispersed all over the United States and Canada.

Except one (and surely some others): Horse of the Year Curlin stayed behind in Saratoga to train there so he is not directly affected by the Belmont situation. He will run at Belmont on September 27 in the Jockey Club Gold Cup.

Equine Herpes virus is a highly contagious disease that has several strains, including some mutations with neurological symptoms that make it difficult for a horse to stand or walk. Hopefully the horse was sick for some other reason.

Dr. Byars to Assess Wellington Situation at Thursday Meeting

The following is a press release received by The Jurga Report from Stadium Jumping Inc., via USEF. Phelps Sports' contact Ken Kraus reported this afternoon that Stadium Jumping is providing the location for the meeting but is not involved in the meeting.

(begin press release)
Wellington, FL – January 3, 2007 – Stadium Jumping, Inc. the producers of the Winter Equestrian Festival, the nation’s largest and longest running equestrian series, has announced that the Jockey Club will once again be made available for an important public forum to discuss the on-going EHV outbreak. The gathering will take place on Thursday morning at 11 a.m. The club is located alongside the Internationale Arena on the showgrounds located at the Palm Beach Polo Equestrian Club in Wellington, Florida.

This will be the second Thursday in a row that area equestrians have assembled at the Jockey Club to discuss the EHV outbreak in Wellington.

“We feel it’s important to make our facility available for these types of community discussions,” said Eugene R. Mische, the President of Stadium Jumping, Inc. “We’re happy that Dr. Byars has agreed to lend his expert opinion to this on-going situation, and I look forward to hearing his assessment of where we’ve been and where we stand now. I also think it’s important,” Mische added, “that our area horsemen have a chance to voice any concerns they may have as we work our way to the start of the 2007 WEF show season.”

The key meeting was requested by Dr. John Steele and Dr. Ben Schachter, two respected Wellington area veterinarians, with over eighty years of experience between them. The meeting was called to bring concerned area equestrians up to date on the current EHV situation in Wellington, and will feature Dr. Doug Byars, the former head of Internal Medicine at Hagyard-Davidson-McGee in Lexington, Kentucky. The panel will also include Dr. Fred Petersen.

Byars is a recognized expert on the EHV virus, and will bring to the meeting his independent assessment of the EHV outbreak in Wellington following a complete tour of the area ‘hot spots’ on Wednesday.

Everyone in the Wellington community is welcome to attend this forum, beginning at 11 a.m. on Thursday.

(end press release)

Background article for horse owners on Equine Herpes Virus and, in particular, EHV-1, from the American Association of Equine Practitioners

Photo: John Steele DVM, show horse specialist veterinarian from Vernon, NY, and Ben Schacter DVM of Wellington Equine Associates in Lake Worth, Florida, were instrumental in bringing equine disease specialist Doug Byars DVM to Florida to assess the EHV outbreak. Dr. Steele travels to Florida in the winter months to provide services to his clients at their winter shows. Photo kindly provided by Kenneth Kraus/PhelpsSports.com