About West Nile Virus
WNV transmission occurs when infected mosquitoes feed on animals, as well as humans, after having fed on infected birds.
Clinical signs of WNV in horses include:
- Mild anorexia and depression;
- Fine and coarse muscle and skin fasciculation (twitching);
- Hyperesthesia (hypersensitivity to touch and sound);
- Changes in mentation (mentality), when horses look like they’re daydreaming or “just not with it”;
- Occasional drowsiness;
- Propulsive walking (driving or pushing forward, often without control); and
- Spinal signs, including asymmetrical weakness; and
- Asymmetrical or symmetrical ataxia (incoordination).
West Nile virus has no cure; however, some horses can recover with supportive care. Equine mortality rates can reach 30-40%. The American Association of Equine Practitioners includes WNV as one of the core diseases all horses should be vaccinated against at least annually.