First Cases of West Nile Virus Reported in 2013

You still have time to help prevent this mosquito-borne illness.

From AQHA Corporate Partner Zoetis

West Nile virus remains a threat to horses. But with the right vaccine and preventive measures, horse owners have time to help protect their horses against this life-threatening disease.

West Nile encephalomyelitis is an inflammation of the central nervous system that is caused by an infection with the West Nile virus. It is transmitted by mosquitoes – which feed on infected birds or other animals – to horses, humans and other mammals.

Horses in Texas and Ohio have tested positive for West Nile virus, the first equine cases reported in the United States this year.1 In 2012, when 690 cases were reported nationwide, only eight states (Alaska, Delaware, Hawaii, Kansas, Maine, New Hampshire, Rhode Island and West Virginia) had no reports of equine West Nile.2

Vaccination remains the most effective way to help protect horses against West Nile and other encephalic or mosquito-borne diseases, such as eastern equine encephalomyelitis and western equine encephalomyelitis. Already this year, 14 cases of eastern equine encephalomyelitis have been reported.3

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WEST NILE-INNOVATOR® + EWT is a trusted vaccine from Zoetis that offers demonstrated protection against West Nile, eastern equine encephalomyelitis, western equine encephalomyelitis and tetanus – all in a single vaccine. The American Association of Equine Practitioners includes West Nile among diseases requiring core vaccinations, along with vaccinations against eastern and western equine encephalomyelitis, tetanus and rabies.4 Conveniently, Zoetis offers four combinations to fit any vaccination protocol: WEST NILE-INNOVATOR, WEST NILE-INNOVATOR + EW, WEST NILE-INNOVATOR + EWT and WEST NILE-INNOVATOR + VEWT. Ask your veterinarian about the right combination for your horse.

In conjunction with vaccination, use good techniques for managing mosquitoes. This includes:

    • Destroying any mosquito breeding habitats by removing all potential sources of stagnant water
    • Cleaning and emptying any water-holding container, such as water buckets, water troughs and plastic containers, on a weekly basis.5

Remember that West Nile virus does not always prompt signs of illness. Horses who do become clinically ill from the virus can suffer a loss of appetite and depression due to an infection of the central nervous system. Other clinical signs may include fever, weakness or paralysis of hind limbs, impaired vision, ataxia, aimless wandering, walking in circles, hyper-excitability or coma.6 Horse owners should contact a veterinarian immediately if they notice signs or symptoms of West Nile infection in their horses, especially ones exhibiting neurological signs. The case fatality rate for horses exhibiting clinical signs of West Nile infection is about 33 percent.4

No matter the location, horses are at risk. By providing proper vaccination and helping manage mosquito populations, horse owners can do their part to help prevent West Nile virus infections. Find out more by contacting your Zoetis representative or visiting

Keep up with the latest health news that could affect you and your horses. Subscribe to The American Quarter Horse Journal today.

About Zoetis

Zoetis (zo-EH-tis) is the leading animal health company, dedicated to supporting customers and businesses focused on raising and caring for livestock and companion animals. Building on a 60-year history as the animal health business of Pfizer Inc., Zoetis discovers, develops, manufactures and markets veterinary vaccines and medicines, complemented by diagnostic products and genetic tests and supported by a range of services. The company generated annual revenues of $4.3 billion in 2012. It has more than 9,300 employees worldwide and a local presence in approximately 70 countries, including 29 manufacturing facilities in 11 countries. Its products serve veterinarians, livestock producers and people who raise and care for livestock and companion animals in 120 countries. For more information, visit

1 U.S. Department of Interior. U.S. Geological Survey. Disease Maps 2013. Updated June 25, 2013. Available at: Accessed on July 1, 2013.
2 U.S. Department of Interior. U.S. Geological Survey. Disease Maps 2012. Updated May 14, 2013. Available at: Accessed on July 1, 2013.
3 U.S. Department of Interior. U.S. Geological Survey. Disease Maps 2013. Updated June 25, 2013. Available at: Accessed on July 1, 2013.
4 American Association of Equine Practitioners. Core Vaccination Guidelines. 2012. Available at: Accessed on July 1, 2013.
5 The Florida Department of Agriculture and Consumer Services: The Division of Animal Industry. West Nile Virus. Updated March 11, 2011. Available at: Accessed on July 1, 2013
6 Pennsylvania’s West Nile Virus Control Program. What Horse Owners Should Know About West Nile
Virus. 2000. Available at: Accessed on July 1, 2013.

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