A yearling Standardbred filly in Elkhart County, Indiana, tested positive for West Nile virus (WNV) on Sept. 29. The filly showed clinical signs on Sept. 16, including mild ataxia and shakiness, but has since recovered.
EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.
WNV 101
West Nile virus is transmitted to horses via bites from infected mosquitoes. Clinical signs in infected horses can include:
- Flulike symptoms such as mild anorexia and depression;
- Muscle and skin twitching;
- Hypersensitivity to touch and sound;
- Changes in mental activity;
- Drowsiness;
- Propulsive walking;
- Spinal weakness;
- Ataxia.
There is no cure for West Nile virus in horses, with mortality rates ranging from 30-40%. Vaccination is an effective prevention method, with annual boosters recommended for previously vaccinated horses and a two-shot series for unvaccinated horses.
In addition to vaccination, owners should take steps to reduce mosquito populations and limit exposure by eliminating stagnant water sources, regularly cleaning water containers, keeping animals indoors during peak mosquito activity times, and using approved mosquito repellents for horses.