Vaccines critical to protect horses from mosquito-borne illnesses

Veterinarians are concerned that horse care providers have been lulled into a false sense of security when it comes to protecting animals from two potentially deadly mosquito-borne illnesses-the West Nile Virus and Eastern Equine Encephalitis.
Traditionally, horse owners have marked the seasonal change from winter to warm weather a round of springtime vaccines for their equine friends. In this part of the country, spring shots typically include inoculations to prevent tetanus, rabies, influenza and rhinopneumonitis, and various forms of encephalitis.
But as alarming reports of animals stricken with serious and frequently fatal illness caused by West Nile Virus (WNV) and Eastern Equine Encephalitis (EEE) have declined, some horsemen have opted not to vaccinate against those illnesses. And that’s why equine health care experts are worried. The threat that mosquito-borne diseases pose to horses is as deadly as ever.
Dr. Joseph Garvin, program manager for the Virginia Department of Agriculture and Consumer Science’s Office of Laboratory Services said declines in the number of reported cases of both diseases in 2007 and 2008 could have been caused by weather conditions and correspondingly, with the population of disease-carrying mosquitoes. But, Garvin added, “It is possible that weather conditions this year may again favor increased mosquito populations. People should not relax their guard.“
Veterinarians advise horse owners to administer vaccinations for West Nile and EEE prior to warm weather and peak mosquito breeding season. Boosters are required every six months.
Unionville-based equine veterinarian Dr. John Moody said WNV and EEE have been less prevalent lately because the vaccines have been effective. But without the continued vaccine and boosters, the number reported cases will once again be on the increase.
Symptoms of equine encephalitis include staggering, circling, depression, loss of appetite, fever and blindness. There is no cure for either disease, which can kill 30 percent of horses infected with WNV, and 90 percent of horses infected with EEE.
While there’s no risk of a human, or even another horse contracting West Nile or Eastern Encephalitis from an infected horse, the fact that a horse has become infected indicates that the risk for additional cases in that geographic vicinity is high for additional cases in any species.
For Burr Hill area horse farm owner Joan Prasse, skipping vaccines simply isn’t a risk she’s willing to take. Prasse operates a multi-breed lesson, boarding and training facility where she oversees the healthcare for close to 40 horses owned by the farm, or private owners.
“I encourage my clients to vaccinate their horses against EEE, WEE, and WNV because the viruses are spread by insect vectors (mosquitos), not just direct contact with another animal, so even isolating your horse won’t protect it,“ Prasse said.
Simply put, she said, it’s better barn management to vaccinate than to risk devastating illness for her horses and those of her clients.
“There is no easy cure for these viruses and there is a high mortality rate for infected animals,“ Prasse said. 
“If people don’t vaccinate, the diseases are going to come back,“ Moody said.