First case of equine West Nile virus for 2019 diagnosed

Chris McGann
Communications

Vaccinating horses against West Nile virus is the best way to
protect them from the disease. 

A quarter horse in Klickitat County tested positive for West Nile virus this week in what has been a light year for the disease. It is Washington’s first reported case this year.

The two-year-old gelding, had not been vaccinated for the disease.

The horse was treated for what appeared to be colic but its condition worsened quickly, becoming ataxic or unable to control its muscles the following day.

The horse’s condition is improving and the referring veterinarian has guarded optimism for its recovery.

Vaccinate your horse

Washington State Veterinarian Dr. Brian Joseph said the disease is not always fatal to the infected horse, but most cases that do prove deadly occur in unvaccinated or incompletely vaccinated animals.

“This is a good reminder for horse owners to protect their animals by vaccinating for this preventable disease,” Joseph said.

According to U.S. Department of Agriculture Animal and Plant Health Inspection Service, 493 equine cases of West Nile virus from 42 states were reported in 2018.

Last year, two horses were diagnosed with West Nile virus statewide, but some years have seen much higher numbers of infected horses. In 2015, 36 cases were reported in Washington, with several horses dying or being euthanized as a result of the disease.

West Nile virus is spread by mosquitoes that have fed on infected birds and while it can sicken people, horses, birds and other animals, it does not directly spread from horses to people or other animals.

Watch for symptoms

West Nile virus is prevalent across the country, so it’s always a good idea to keep an eye out for signs of infection in horses. Closely observe your horse and look for signs, which include:

• Fever of 102.5 degrees F or higher
• Discharge from eyes or nose
• Limb edema or swelling
• Spontaneous abortions
• Neurologic signs such as an unsteady gait, weakness, urine dribbling, lack of tail tone and recumbency.

Veterinarians who diagnose potential West Nile virus cases should contact the State Veterinarian’s Office at (360) 902-1878.

Visit WSDA’s West Nile virus webpage or the state Department of Health for more information.

Slow start for West Nile virus

Chris McGann
Communications

A Grant County Quarter Horse named Tiny tested positive for West Nile virus last week. According to WSDA Veterinarian Dr. Brian Joseph, the five-year-old gelding is the first horse in Washington identified with the disease this year.

Horses' best protection against West Nile virus is vaccination. 

Although West Nile virus can be fatal, Tiny is receiving care for a neurological deficit in the right rear and his prognosis appears to be good.

Last year, nine horses were diagnosed with West Nile virus statewide, and just two years earlier, 36 cases were reported in Washington, with several horses dying or being euthanized as a result of the disease.

Joseph said the positive test comes as no surprise.

“It happens every year,” he said. “But this is a good reminder. It’s so easy to prevent if you vaccinate.”

Horse vaccination for West Nile virus  requires two doses and annual boosters. It is most effective when given to horses in spring, before mosquito season.

“But it’s never too late to vaccinate,” Joseph said. “It’s so easy to prevent it.”

Records indicate Tiny may have received one of the West Nile virus vaccinations which may have helped reduce the danger.

“There’s about a 30 percent mortality for horses showing severe neurological symptoms,” Joseph said. “Most horses show milder, flu-like symptoms or no symptoms at all.”

West Nile virus is spread by mosquitoes that have fed on infected birds and while it can sicken people, horses, birds and other animals, it does not directly spread from horses to people or other animals.

“People and horses are “dead end” hosts,” said Joseph, explaining that the disease does not travel directly from horse to horse – or person to person.

Other preventative measures include mosquito control, which reduces the horses’ contact the main vector or the disease. Circulating air around stalls can really help.

West Nile virus is not spread between horses. Mosquitoes are
the main vector, passing the virus from birds, such as crows. 

This first West Nile virus case showed up a little later in the year than normal, the dry hot weather may have contributed by reducing the habitat for mosquito larva, Joseph said.

Watch for symptoms

West Nile virus is prevalent across the country, so it’s always a good idea to keep an eye out for signs of infection in horses. Closely observe your horse and look for signs, which include:

• Fever of 102.5 degrees F or higher
• Discharge from eyes or nose
• Limb edema or swelling
• Spontaneous abortions
• Neurologic signs such as an unsteady gait, weakness, urine dribbling, lack of tail tone and recumbency.

Veterinarians who diagnose potential West Nile virus cases should contact the State Veterinarian’s Office at (360) 902-1878.

Visit WSDA’s West Nile virus webpage or the state Department of Health for more information.

Spring is here – time to vaccinate your horse for West Nile virus

Dr. Thomas Gilliom
WSDA field veterinarian 

Mosquito season is upon us which means it’s time to make sure your horses are vaccinated for West Nile virus. Washington often reports more cases of West Nile virus in horses than most other states in the nation, making vaccinations all the more important.

Usually, most confirmed cases of West Nile virus are in the central and eastern part of our state. Cases crop up beginning in late spring and through the summer and fall, which is also prime mosquito season.

Since the virus spreads by mosquitoes, there are no mass outbreaks affecting several horses at once, but rather just one or two cases at a time. Last year, nine horses were diagnosed with West Nile virus statewide, but just two years earlier, 36 cases were reported in Washington, with several horses dying or being euthanized as a result of the disease.

West Nile virus is spread by mosquitoes that have fed on infected birds and while it can sicken people, horses, birds and other animals, it does not directly spread from horses to people or other animals.

Most horses exposed to the West Nile virus don’t show any symptoms. When they do become ill, however, symptoms can include lack of coordination, loss of appetite, confusion, fever, stiffness, and muscle weakness, particularly in their hindquarters. The disease is fatal in about a third of the cases where these symptoms show up.

West Nile virus can be prevented with vaccination and spring is when horse owners should plan to include West Nile virus with annual equine vaccinations.

The vaccine is most effective when given to horses early in the mosquito season. Horses require two doses of the vaccine initially, and then boosters at least annually.

Use insect repellent and fly sheets to reduce exposure to mosquitoes. Also,look for and eliminate areas with standing water where mosquitoes can breed. Get rid of old tires or other areas where rain water can accumulate. It’s even a good idea to refresh the water in water troughs weekly.

Veterinarians who diagnose potential West Nile virus cases should contact the State Veterinarian’s Office at (360) 902-1878.

Visit WSDA’s West Nile virus webpage or the state Department of Health for more information.

West Nile virus season waning; Nine horses test positive

Mike Louisell
Communications

Washington state had far fewer cases in 2017 of horses infected with West Nile virus than last year.

This year, the West Nile virus was confirmed in nine horses statewide. If the number holds firm, that is far less than the 27 West Nile equine cases recorded in 2016. Most of the horses struck with the disease were not vaccinated. While some of the horses recovered from the illness, others had to be euthanized. 

The nine cases reported this year were confined to four counties. Spokane County had six. Benton, Lincoln and Kittitas counties each had a single horse case confirmed by laboratory testing. Last year, cases of West Nile virus in horses were recorded in 10 counties, all located in Eastern Washington, with Spokane County reporting eight of the illnesses.

The disease can be fatal to horses especially if they show advanced neurological signs. The best way to prevent West Nile virus in horses is by vaccination—a message you’ll be hearing again from WSDA veterinary staff next spring.

The disease is spread by mosquitoes that have fed on infected birds. It does not spread directly from horses to people or other animals. Cold weather, particularly a good freeze or two, will take care of mosquito threats until next spring.

Visit WSDA’s Animal Health webpage for tips on minimizing the risk of West Nile virus for your horses, or go to www.doh.wa.gov/wnv for more information about West Nile virus activity in our state, including human cases. 

Horses hit hard with West Nile virus in northeastern WA

Mike Louisell
Communications

Photo credit: Erin Danzer

Ten confirmed cases of West Nile Virus in horses have been detected so far this year in Washington, with the most recent cases in Stevens, Pend Oreille, Lincoln and Spokane counties. Warmer weather seems to have prompted the spread of mosquitoes carrying the West Nile virus into these northeastern parts of Washington.

The first case of the year came in late July involving a horse in Grandview, Yakima County, the state’s traditional hotspot for the West Nile virus. Since then, the Washington Animal Disease Diagnostic Laboratory (WADDL), operated by Washington State University in Pullman, has reported nine additional horse cases to WSDA.

The cases include:

• A horse in Creston, Lincoln County, in guarded condition. It had not been vaccinated for West Nile virus.
• A horse in Sprague, Lincoln County, in fair condition. It was vaccinated as a foal and yearling. 
• A horse near Elk, Stevens County, has been euthanized. It was not vaccinated.
• A horse in Kettle Falls, Stevens County, in guarded condition. It was not vaccinated.
• A horse in Colville, Stevens County, in fair condition. It was vaccinated.
• A horse in Newport, Pend Oreille County, is in fair condition. It was not vaccinated.
• A horse in Cheney, Spokane County, is in fair to good condition. It was not vaccinated.
• A horse in Cheney, Spokane County, died recently. Tissue tested positive for West Nile virus. Vaccination history unknown.
• A horse in Deer Park, Spokane County, is in fair condition. It was not vaccinated.
• The horse in Grandview, Yakima County was showing neurologic signs including stumbling and difficulties eating when the case was reported in late July. It was not vaccinated. It was the first horse report for 2016.

Washington had 36 confirmed cases of horses with West Nile virus last year, leading the nation with nearly 17 percent of confirmed equine cases. The virus is spread by mosquitoes that have fed on infected birds. The disease sickens people, horses, birds and other animals, but it does not spread directly from horses to people or other animals. The risk of a horse becoming ill lingers into fall.

Vaccinations against West Nile virus and reducing mosquito populations are the main strategies for protecting your horse. Spring is the best time for the vaccination but some veterinarians say it’s never too late to vaccinate for some protection against the virus.

Other tips include:
• Remove standing water from yards and barns that can serve as a breeding ground for mosquitoes, including old tires and garbage that may be rain soaked.
• Change water at least weekly in troughs or bird baths.
• Keep horses in stalls or screened areas during early morning and evening hours when mosquitoes are most active.
• Put fans inside bars and stalls to maintain air movement.

Visit our West Nile virus webpage for more on protecting your horse against this disease.

Don't overlook value of West Nile virus shots for your horses

By Joe B. Baker, DVM

Washington State Veterinarian

One week ago the count of horses confirmed with West Nile virus in our state totaled 10 cases. As of Wednesday, it has climbed to 18 cases.

The first case was reported in late July in Benton County, and since then there have been cases reported in six more counties, including Adams, Franklin, Grant, Kittitas, Lincoln and Yakima counties. The south-central portion of our state has historically been where most of the West Nile virus infections are documented each year. After experiencing a significant number of cases in the region in 2008 and 2009, there had been relatively few cases in horses reported in 2010-2014. Five cases were reported in 2014.

Photo: Erin Danzer

Unfortunately, none of the horses reported this year had current booster shots for West Nile, and many of them had never received any vaccination for the disease. After several consecutive years with few or no cases, horse owners may have been lulled into thinking that vaccinations for West Nile virus did not have to be included in their horse’s annual shots. In one case the owner had reportedly been advised by their trainer that vaccinations in horses were a waste of time.

About half of the virus-infected horses reported this year in our state have either succumbed to the disease or have been euthanized. Statistically, 40 percent of those horses that recover will be likely to have long-lasting if not permanent neurological deficits. 

I would like to make a personal plea to all horse owners in Washington to include a West Nile virus shot as a core vaccine in your horse’s vaccination schedule.  The American Association of Equine Practitioners considers the core vaccinations for horses to be eastern/western equine encephalitis, tetanus, rabies and West Nile virus.

The American Veterinary Medical Association defines core vaccinations as those “that protect from diseases that are endemic to a region, those with potential public health significance, required by law, virulent/highly infectious, and/or those posing a risk of severe disease. Core vaccines have clearly demonstrated efficacy and safety, and thus exhibit a high enough level of patient benefit and low enough level of risk to justify their use in the majority of patients.”

Typically Washington’s mosquito season lasts until freezing temperatures return in the fall. If you have a horse that has been given West Nile virus vaccine in the past, it is not too late to give it a booster. Boostering a previously vaccinated horse usually induces a rapid rise in immune levels. If you have never vaccinated your horse in the past, it will take two shots about a month apart to establish immunity.  So you could still manage to protect your horse for the last few weeks of this year’s mosquito season if you start now!

Count stands at 10 horses with West Nile virus—all in Eastern Washington

By MikeLouisell

Communications Office

We now have 10 cases of horses struck with the West Nile virus, with those horses spread across seven counties in Eastern Washington.

West Nile virus is a disease carried by mosquitoes which can be fatal to horses. Symptoms include loss of appetite, lethargy and loss of coordination. Horse owners are urged to keep horses indoors at dawn and dusk, when mosquitoes are prevalent, especially if their horses have not been vaccinated against West Nile.

There's still time to vaccinate for this mosquito season. And, for greater comfort for your horses, consider insect repellent sprays or wipes, fly sheets or fly-repellent feed supplements.

The newest West Nile virus cases have been found in Grant, Kittitas and Lincoln counties and include:

• A 9-year old Quarter horse mare in Moses Lake which became ill but is improving with treatment. That horse was last vaccinated for the virus four years ago.
• A 5-year old Quarter horse mare in Moses Lake contracted the virus and was euthanized. There was no vaccine history for this horse.
• A 14-year old Quarter horse gelding in Ellensburg contracted the virus and was euthanized. It appeared the horse had not been vaccinated for at least the past five years. 
• A 5-year old Appaloosa mare in Almira became ill and was euthanized. It did not appear that the mare had been vaccinated for the virus.

This summer, there have been several cases of horses with West Nile virus in Adams, Benton, Franklin and Yakima counties. So far, no equine cases involving Western Washington horses have been reported. 

West Nile virus is a reportable disease, so veterinarians who learn of potential cases in horses or other animals should inform the State Veterinarian’s Office in Olympia by calling (360) 902-1881.