There has been a lot of talk in the news lately about the West Nile virus, and we are starting to get a few questions from clients wanting information on it.
West Nile virus is spread when a mosquito feeds on an infected bird, and then subsequently passes it on to another animal. Since the original epicenter of New York in 1999, the disease has spread through 18 Atlantic and Gulf states. Florida's equine population has been the hardest hit, but Colorado so far remains West Nile virus-free.
Once infected, the virus can cause encephalitis (inflammation of the brain), with the most common signs of infection in the horse being: stumbling or incoordination; weakness of the limbs; partial paralysis; muscle twitching ("the Shakes"); hypersensitivity to touch; and death, killing about 35% of diagnosed horses. The signs are virtually indistinguishable from all three strains of equine encephalitis (EEE, WEE, and VEE), Equine Herpes Virus Type-I, and EPM, therefore diagnosis through blood samples is essential.
The treatment of the WNV consists of supportive therapy, including IV fluids, anti-inflammatories (both steroidal and non-steroidal), Vitamin E, and a safe area to protect the horse from getting hurt. Most horses will recover, however residual effects are still largely unknown.
The best means of prevention is by reducing the exposure to mosquitoes and administering a vaccination. Stalls and water troughs should be kept clean, stagnant water eliminated, insect repellant applied, and stalling horses at night will all aid in reducing the exposure to mosquitoes. A West Nile virus vaccination has recently been conditionally approved and is just now being made available to veterinarians in the East. Due to the East's current need for the vaccine, all supply is going to them and so, as of yet, it has not been made available to the Western portion of the United States. We are carefully monitoring the spread of this disease as it moves closer to our state. We are also discussing vaccination protocols for our area so that, if necessary, we can be prepared for next years mosquito season.