b'TINY TERRORSexperience persistent neurologic deficits. veterinarian about recommendations for Horses older than 15 are more at riskvaccination frequency relative to your of developing severe neurologic signsgeographic environment. from WNV and dying as a result. HorsesIt is also important to involve your that develop signs from WNV later inveterinarian in the immunization process. mosquito season (which varies by regionRESERVOIR HOST To optimize an immune response, the but occurs when temperatures are consis- vaccine must have been handled appropri-tently above 50 degrees) have a less favor- ately (distribution to administration), not able prognosis for survival than horsesbe expired, and be properly administered that fall ill earlier in the season. to a healthy horse, says Vaala, some-In contrast to EEE, WNV isnt as local- thing the veterinarian is best-equipped to ized to specific regions of the country be- INTERMEDIATE do. Moreover, major vaccine producers cause various mosquito species that liveVECTOR offer a vaccine guarantee that provides throughout the United States and Canadafinancial support for diagnostic work-ups carry and can transmit the virus. In tem- and treatment of horses that have con-perate climates WNV tends to appear intracted one of the core diseases despite mid- to late summer, lasting until a killinghaving been properly immunized with a frost eliminates mosquito vectors. Casesveterinarian- administeredvaccine. in 2019 occurred primarily in CaliforniaAnother point to consider for preven-(15), Colorado (10), and Florida (10).tion revolves around turnout time horses turned out at dusk or dawn are Preventing Disease exposed to more mosquitoes than if they Owners can protect their horseswere confined in stalls with fans and/or from EEE, WEE, and WNV withinsect sprays during those hours. Vaala annual vaccination. All horses are atsays mosquitoes have difficulty landing risk of contracting mosquito-borneDEAD-END and feeding in a constant breeze. She also viruses if not immunized correctly.HOSTS recommends applying mosquito repellent Owners are fortunate to have accesslabeled for equine use.ISTOCK.COM PHOTOSto effective EEE and WEE vaccinesComprehensive mosquito control and several effective WNV vaccinesremains an important part of any preven-developed and labeled specifically fortion strategy, she says. horses. To date, no vaccines have beenRemove all standing or stagnant water developed for humans against thesethat can serve as mosquito breeding habi-diseases. The equine vaccines are verytats to reduce populations on your farm. safe, inexpensive, and highly efficacious.administer the vaccine booster annually,Even the least suspected container is a Properly vaccinated horses appear to bepreferably at least two to four weeks priorrisk, including persistent puddles around adequately protected, says Vaala. to your regions anticipated mosquitowater tanks or in tire tracks. Water Horses that have not received a full se- hatch.troughs, wheelbarrows, clogged gutters, ries (two to three injections spaced threeThese vaccines provide effectiveditches, nonchlorinated pools, decorative to six weeks apart) of the initial immu- viral immunity for four to six months.ponds, bird baths, flowerpots, buckets, nizations or a yearly booster are at riskVeterinarians recommend twice-annualabandoned tires, tarps, holes in trees, of contracting disease. The Indiana stateboosters in areas of the country wheremanure piles that collect water, culverts, veterinarians office released a statementmosquito populations persist due to mildand even discarded jars, soda cans, or about its 11 EEE cases in 2019, notingweather year-round.water bottles are potential breeding sites all affected horses were unvaccinated,In an unusually warm and wet year,for mosquitoes. Discard or drain such and clinical signs progressed quickly. Themore frequent EEE vaccination iswater-holding receptacles regularly. one horse that survived had a history ofwarranted, says Vaala. Also, owners vaccination but was not up to date.shipping horses south for winter showsPotential Effects of Climate ChangeA similar trend occurred in Michigan:should make certain their horses areWhile scientists have not yet come to a Eighty-six percent of the equine casesproperly immunized against mosquito- consensus about climate change and how were either unvaccinated or had notborne diseases.it does or will affect various ecosystems, received an annual vaccination for atVaccination frequency is bestrecent trends could shed light on how least a year, says state veterinarian Noradiscussed with a horse owners veteri- mosquito-borne disease might fare in the Wineland, DVM, MS, Dipl. ACVPM. narian, says Wineland. Vaccines arefuture. Over a 20-year period Canadian Indeed, horses that have receivedlicensed based on studies completedresearchers reported seeing a 10% in-the initial two- to three-part series ofby the manufacturing company as partcrease in human cases of mosquito-borne EEE/WEE or WNV vaccines are notof the approval process. Studies thatdisease. The United Nations Intergov-protected forever. Your veterinarian mustreview duration of immunity inform yourernmental Panel on Climate Change TheHorse.com|The HorseApril 202019'