West Nile Virus

     West Nile Virus (WNV) causes encephalitis in birds, horses and humans.  The virus is transmitted from infected birds by mosquitoes.  Humans and horses appear to be especially susceptible.  Studies show that infected horses will not transmit WNV to other horses or to people.  However care should be taken when handling blood from suspect animals.

     West Nile Virus first showed up in North America in the early 90's.  It systematically spread over almost  of our continent  over the next few years.   British Columbia, Yukon and NorthWest Territories were spared. 

This has now changed.  This September, 2011, we diagnosed the first case of West Nile virus disease in a horse in the Kelowna area.  See the link on this web page to our West Nile update. 

 

Symptoms of disease caused by WNV may include the following:

    * Flu-like signs (fever and depression)
    * Skin twitching, especially around the muzzle.
    * Hypersensitivity to touch and sound
    * Driving or pushing forward without control
    * Incoordination

 

     Because permanent neurological problems and death can occur, early recognition and initiation of treatment is important.  No specific treatment protocol exists however most cases will resolve with supportive therapy and anti-inflammatories.

     Typically, what has happened in the rest of the country is that it shows up in small numbers the first year, then many more cases in the next few years, then seems to decrease as most horses either get vaccinated or get the disesase to some extent.  Those that do not die may develop temporary immunity.

Efforts to prevent disease in horses caused by WNV is through the use of the West Nile Vaccine  and through actions that will reduce exposure to mosquitoes.  The vaccine is safe and  very effective. AAEP vaccination guidelines recommend vaccinating  once a year.

     The most effective way to limit the mosquito population is to destroy the mosquito larval habitat.  This is done by reducing the amount of standing water.  Water troughs should be cleaned at least once a week.  Keeping weeds trimmed and lawn mowed help eliminate areas where mosquitoes rest.  Directly protecting horses from mosquito bites is more difficult.  Fly and mosquito repellents may be helpful.  Products containing pyrethroids are considered safe for horses.   Spray stalls, aisle walls and other areas such as under shade trees where horses congregate.  Fans can also be used to discourage mosquitoes from residing in your barn.