West Nile Vaccine for Horses
The West Nile virus was first discovered and found to be the cause of fatal inflammation of the spinal cord and brain in humans and horses in Egypt, Uganda and France in the early 1960’s.
In 1999, the first cases were discovered in the Western Hemisphere in humans, dogs, cats and horses. Since then the virus has spread throughout the United States, Canada, Mexico, the Caribbean and Central America.
The West Nile virus is most commonly found in birds however it may also infect humans, horses, dogs, cats, bats, chipmunks, skunks, squirrels, rabbits, crows, robins, crocodiles, and alligators.
The virus is transferred by mosquitoes from an avian host to other species. Fortunately, once infected these species, specifically humans and horses, do not contribute to further transmission of the virus. As well, West Nile virus is not directly contagious from horse to horse or horse to human. This is due to the fact that there is not enough of the virus circulating in the blood of these species for it to be transmitted.
When a horse becomes infected with the virus signs may not be visible for up to 15 days. Following this incubation period, signs of West Nile in horses may include fever, stumbling or incoordination, depression or apprehension, stupor, behavioral changes, weakness of limbs, partial paralysis, droopy lip, teeth grinding, muscle twitching, tremors, difficulty rising, convulsions, blindness, stomach pain, and intermittent lameness, or even death.
The death rate in horses affected by the West Nile virus is estimated to be 33%. Of those that do not suffer death, approximately 40% experience enduring effects for up to 6 months following diagnosis.
The full extent of the effects of West Nile is still widely unknown and therefore it is recommended that all horses in North America be immunized against the virus.
Along with immunization, preventative measures can be taken to reduce the risk of infection. Efforts to control mosquito populations can be made by ensuring that stagnant and standing water is eliminated or reduced, removing old tires, keeping horses in the barns from dusk to dawn (prime mosquito feeding times), setting out mosquito traps, keeping air moving with fans, and removing muck as much as possible. Other solutions such as mosquito repellants that are approved for use with horses and stall deodorizers and moisture control products like Stall DRY can be used as well.
Although disease can not be fully prevented with use of the immunization, the vaccine is the primary method of risk reduction.
Please talk to your veterinarian about taking this preventative measure in order to ensure the health and safety of your horses.
Please Note: This information has been gathered from various resources however it is not to be substituted for the advice of a veterinarian. Please consult a professional for information regarding the use of this vaccination before proceeding.
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