Four Californian horses tested positive for the West Nile virus (WNV), reported the California Department of Food and Agriculture (CDFA). This brings the total number of confirmed horse WNV cases in California to five in 2018.
"On August 16, four horses showing neurological signs were confirmed positive for the West Nile virus," states the CDFA:
- A 9-year-old vaccinated quarter horse mare in the Sacramento County;
- A 3-year-old unvaccinated Andalusian mare in Kern County
- A 6-year-old vaccinated quarterback horse gelding in Placer County; and
- An 8-year-old unvaccinated Hanoverian mare in Sacramento County.
"Due to the severity of the neurological signs, the 9-year-old Quarter Horse mare in Sacramento and the 3-year-old Andalusian mare in Kern County has been euthanized," the CDFA said. "The other two horses are alive and cared for by veterinarians."
California's other WNV case has been confirmed in an unvaccinated Shasta County horse. This animal did not survive.
"CDFA constantly monitors and investigates equine neurological cases for the presence of WNV in California," the agency said. "CDFA urges horse owners to consult their veterinarian regarding a WNV vaccination program to ensure maximum protection for their horses."
West Nile virus is transmitted to horses via bites from infected mosquitoes. Not all infected horses show clinical symptoms, but those who can do so can show:
- Flulike signs where the horse appears slightly anorexic and depressive;
- Fine and rough muscle and skin fasciculation (twitching);
- Hyperesthesia (19659005) Changes in mentality when horses look as if they daydream or "just not with it";
- Occasional drowsiness;
- Propulsive walking (driving or pushing forward, often without
- Spinal signs, including asymmetric weakness, and
- Asymmetric or symmetric ataxia
West Nile has no cure, however, some horses may recover with supportive care.The mortality rates of horses may be 30 -40%.
Studies have shown that vaccines can be effective WNV prevention tools Horses vaccinated in recent years need an annual booster dose, but veterinarians might recommend two booster a year – one in the spring and one in the spring more in the autumn areas with extended mosquito season n previously unvaccinated horses within three to six weeks a vaccine series with two vaccinations. Full Immunity Lasts Several Weeks
In addition to vaccines, owners should work to reduce mosquito populations and breeding grounds and limit the mosquito exposure of horses by:
- removing stagnant water sources;
- Dumping, cleaning and regular replenishment of buckets and troughs
- Keeping of animals during feeding times of beetles (typically early in the morning and in the evening); and
- applying mosquito repellents approved for use in horses