For the Health of It such as irrigation ditches , rivers , or streams . Adult flies move outward from these areas . Some can only fly short distances ( sand flies ), but others fly longer distances ( black flies ) or travel on wind currents ( black flies , midges ). Seasonality of the vectors coincides with warmer months , spring through fall , but midges can be more cold-hearty and occasionally transmit VSV in winter . Preferred feeding / biting times vary , with sand flies being night feeders , biting midges feeding around sunrise and sunset , and black flies feeding during the day . Vector mitigation strategies should be considered at the neighborhood , premises , barn , and animal level . At the neighborhood level , keep animals away from insect emerging sites such as moving water and standing water during the insect seasons . Alternatively , time the rotation of animals through pastures to avoid grazing near a stream returning to base flow after reaching peak runoff , a time of black fly emergence . If possible , move animals to higher-elevation pastures during the vector season . At the premises level , removing manure regularly , maintaining sloped and well-drained footing around water sources , and keeping surrounding vegetation mowed will also reduce insect vectors .
At the barn level , move animals indoors during vector feeding times or provide access to a run-in shed for pastured horses . Installing mesh netting or
repellent-treated fabrics on barn openings can further prevent vector entry . Minimizing the use of bright lights at night and adding fans blowing down onto horses can also be preventive . At the animal level , topical insecticides and repellents reduce exposure to biting insects , but repeated application is necessary and must be combined with insect mitigation at the other levels to be effective . Using fly sheets , masks , leg wraps , and ear covers with or without repellent fabric are also animal-level mitigations , but these must cover the areas where VSV lesions occur . Therefore , chemical repellents may need to be used in conjunction with fly sheets and masks to protect the muzzle and lips .
Mitigation strategies and biosecurity measures at multiple levels are needed to provide adequate protection from VSV . For more information access “ Management Strategies for Reducing the Risk of Equines Contracting Vesicular Stomatitis Virus in the Western United States ” at the following link :
https :// doi . org / 10.1016 / j . jevs . 2020.103026 .
CONTACT : Angela Pelzel-McCluskey , DVM , MS , Equine Epidemiologist
Angela . M . Pelzel-McCluskey @ aphis . usda . gov ( 970 ) 494-7391
USDA-APHIS-Veterinary Services Fort Collins , Colorado
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