California has confirmed that a 2 year old Andalusian mare is in danger, after not being vaccinated against the West Nile Virus. The mosquito-borne neurological disease has already infected 5 other horses in California since the beginning of the year.
On the 30th of August, officials at the California Department of Agriculture confirmed that a 2 year old mare contracted the West Nile Virus at a Kings County training facility. The Andalusian, which was unvaccinated against WNV, started showing signs of an infection on August 19th. The mare had a fever, inappetence, was stumbling, uncoordinated and had increased lung sounds. She has been reported as alive, but no information about her general condition has been released.
According to the CDFA, the filly is California’s fifth conformed equine case of WNV in 2021. Previous cases resided in Fresno County, where 2 cases were reported, Merced County (1 case), and Sacramento County (2 cases). Reportedly four of the infected horses in California were unvaccinated. Fiveof the six infected horses have survived, one has passed away.
About West Nile Virus
West Nile Virus is the leading cause of arbovirus encephalitis in horses and humans in the United States. Since 2015, more than 25,000 cases of WNV have been reported in U.S. horses. Horses represent 96.9% of all reported non-human cases of WNV disease. West Nile Virus 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
- 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
- Spinal signs, including asymmetrical weakness
- Asymmetrical or symmetrical ataxia
Even though there is no cure for WNV, some horses have been known to recover with a lot of supportive care from a veterinarian. The mortality rates in horses are between 30% and 40%. The American Association of Equine Practitioners reccomends WNV as one of the main diseases all horses should be vaccinated against anually. This is an essential standard of care for all horses in North America.