Protecting Your Horse from WNV Contact Information: A vaccine is available as an aid in control of WNV in horses. The vaccine is safe and has been shown to provide protection in horses. Michigan Department of Agriculture and The WNV vaccine is similar to vaccines Rural Development against EEE and WEE and is only available Animal Industry Division through licensed veterinarians. P.O. Box 30017, Lansing, MI 48909 www.michigan.gov/mdard Horses vaccinated against EEE, WEE, and www.michigan.gov/westnilevirus Venezuelan equine encephalitis are not protected against WNV infection. Horse owners are advised to consult their Monday-Friday, 8:00 A.M. – 5:00 P.M. veterinarian concerning WNV vaccination of 1-800-292-3939 or: their horses. Vaccinated horses can be differentiated from infected horses on Weekends or after hours laboratory tests. (517) 373-0440

In addition to the vaccine for horses, simple insect control measures should be utilized. Consider the use of insect repellents, and place horses in barns/stables under fans Equine WNV testing specimens should be during dusk, dawn, and other times when accompanied by the submission forms Diagnosis and Prevention Tips mosquitoes are present. Eliminate opportunities for mosquito breeding by draining available at each laboratory’s website. wet areas of pasture, filling puddles, repairing eve troughs, gutters, etc., clearing any containers that might hold even small pools of Diagnostic Center for Population and water, and draining water tanks once or twice Animal Health weekly. Additionally, consider control of 4125 Beaumont Road mosquitoes in ponds and large water Room 122 containers through the use of larvacides Michigan State University and fish. Lansing, MI 48910

(517) 353-5275 www.animalhealth.msu.edu. Reporting WNV and Other Reportable Animal Diseases or: West Nile Virus is a reportable animal disease. If you suspect an animal has WNV, please National Veterinary Services Laboratory contact your veterinarian, as well as report the USDA-APHIS-VS-NVSL case to MDARD at (517) 373-1077. 1920 Dayton Avenue Ames, IA 50010 Michigan Department of Agriculture & (515) 337-7266 Rural Development and www.aphis.usda.gov/animal_health/ Michigan State University, lab_info_services/. College of Veterinary Medicine and Department of Animal Science

What is West Nile Virus? Birds: the Primary Reservoir Diagnosis of WNV in Horses West Nile Virus (WNV) is a mosquito-borne Species for WNV Diagnosis of WNV infection in horses involves virus that causes encephalitis (inflammation of WNV infects and multiplies in birds, which testing the blood serum for antibodies. the brain) and/or meningitis (inflammation of serve as the reservoir species for the virus. Horses vaccinated for WNV and foals of the lining of the brain and spinal cord). The impact of the disease in birds varies, with positive-testing mares are likely to have a Outbreaks of WNV have occurred in Egypt, American crows frequently dying from the positive blood test for the virus. Veterinarians Asia, Israel, Africa, and some parts of Europe, infection. Many other bird species survive consider blood test results, clinical symptoms Australia and the United States (U.S.). The infection with mild or no indication of disease. and the possibility of other neurological virus was first found in the U.S. in 1999 in New diseases, including rabies, Eastern Equine York City, and has since spread nationwide. WNV is spread from bird to bird by mosquitoes Encephalitis (EEE), Western Equine when they bite birds infected with the virus. Encephalitis (WEE), Equine Rhinopneumonitis WNV in Horses Mosquitoes are also capable of spreading the (equine herpes virus type 1), and Equine Most horses bitten by carrier mosquitoes do virus to horses, humans, and other mammals. Protozoal Myeloencephalitis (EPM), before not develop disease. Of those that do, Birds may have a significant impact on the making a diagnosis. approximately one-third develop severe spread of the virus across the U.S. disease and die or are so affected that Blood or cerebral spinal fluid samples should euthanasia is required. The time between the Birds infected with WNV may show signs such be collected by a veterinarian and sent to the bite of an infected mosquito and when clinical as the inability to fly, incoordination, abnormal National Veterinary Services Laboratory or to signs appear, ranges from three to 14 days. movements, and death. the Diagnostic Center for Population and Animal Health (DCPAH) at Michigan State Although horses do not usually develop clinical WNV in Other Mammals University. Because of the potential for rabies symptoms of WNV infection, horses that are ill Animals other than horses or humans may be and the related risk to humans and animals, vary in symptoms from mild signs to serious susceptible to WNV, but rarely become ill. the heads of horses that die or are euthanized and near death. Typical signs include muscle Antibody has been found in blood samples due to neurological disease should be trembling, skin twitching, ataxia from bats, cats, chipmunks, gray squirrels, submitted to DCPAH. Addresses and (incoordination, stumbling, limb weakness) that domestic rabbits, eastern striped skunks, contact information are listed on the back of either appears suddenly or appears gradually cows, sheep, and pigs. this brochure. and worsens, sleepiness, dullness, listlessness, facial paralysis (droopy eyelids, There is no evidence that infected horses, Treatment and Long-term lower lip), difficulty with urination and humans, or other animals are able to transmit the virus to other animals, people, or Effects of WNV defecation, and an inability to rise. Some Currently, there is no specific treatment for horses may develop mild fevers, blindness, mosquitoes. Only a wild bird/mosquito WNV in horses. Supportive therapy should be seizures, and other signs. transmission cycle has been proven as a means of transmitting WNV. administered by the horse owner’s veterinarian to reduce clinical signs and the possibility for WNV may cross the placenta from mother to gestating foal. Horses cannot spread the secondary infections. When a horse becomes disease to humans, but humans are infected, with or without clinical disease, that susceptible to the disease if bitten by a carrier horse develops antibodies in response to the mosquito. No transfusion related horse infection. Infected horses can acquire long illnesses have been reported. However, human lasting immunity to WNV after recovery, due to to human transmission via blood transfusions these antibodies. If the horse develops have been confirmed, so this method of encephalitis, there may not be full recovery transmission is possible in horses. and the horse may possibly have permanent central nervous system damage.