FALCON CREEK FARM NEWSLETTER

(September 2003)

WEST NILE VIRUS

West Nile virus has steadily spread westward across the U.S. and has reached Colorado with a vengeance. It seems there is a story about the West Nile virus outbreak on every newscast. Almost every day you can find an article about it in one of the local newspapers, and every horse magazine has published an article about it in the last few months. It's hard not to be alarmed, but taking sensible precautions can minimize the risk of your horse getting sick from it.

West Nile is a virus that is transmitted by blood-feeding insects - specifically, various types of mosquitoes. Most West Nile virus (WNV) infections do not cause any illness, either in people or in horses. In relatively rare cases and in high-risk groups, such as the elderly, the virus can overwhelm the immune system and can cause encephalitis, an inflammation of the brain and spinal cord. This is what makes it fatal.

Since the virus was first isolated in the U.S. in September 1999, 305 people have died from West Nile encephalitis (WNE), and an estimated 4,500 horses have died. Because of this high incidence of mortality in horses, a vaccine has been developed, and has just recently been FDA approved. Horses should receive one dose in early spring, followed by a booster 3-6 weeks later. According to studies done by Fort Dodge Animal Health, the vaccine's manufacturer, 95% of horses that received both doses of the vaccine remained healthy a year later. Several horses here at Falcon Creek have recently been given a third dose of the vaccine to protect them during the height of the Colorado mosquito season in late August and early September.

Only a small percentage of horses that have the virus present in their blood ever actually contract encephalitis. Of those horses that actually get symptoms of it, approximately 70% will recover. However, recovery often takes several months, and about 1% of all horses that have had WNV will never fully recover. These horses are usually euthanized. Breed, gender and age don't seem to have an effect on whether a horse will contract West Nile, so it's important to have all horses vaccinated (consult with your vet about foals, and pregnant mares).

If your horses haven't been vaccinated yet this year, it is too late to protect them in the next couple of months. The vaccination isn't really effective until the second booster shot has been given. The main line of defense against West Nile is reducing the mosquito population around your barn. Here are a few steps you can take to safeguard your horses.

* All sources of standing water should be eliminated if possible. Get rid of old tires, empty planters, and anything that can collect even a small amount of water. Prop up wheelbarrows when you aren't using them.

* During the summer, clean out water troughs at least once a week. The more polluted the water, the more mosquitoes like it for their breeding grounds.

* Keep gutters clear of leaves and debris. Fill in any ditches that collect water.

* Spray your horses with bug repellant designed to repel mosquitoes, and use it often.

* Use fans in your barn to increase air circulation and make it harder for mosquitoes to land on your horses. Keep your horses in their stalls at daybreak and dusk, when mosquitoes are most active.

* Keep barn lights off after dusk. Turning on a light that's positioned around the perimeter of the barn will attract mosquitoes away from your horses.

Keep an eye on your horses for any sign of WNV. Some signs occur more often than others. The most common symptoms are:

* Muscle weakness and ataxia (stumbling, swaggering, lack of coordination especially in the hind end)

* Fever of 101 degrees or higher for two days or more

* Loss of appetite

* Muscle twitching (often seen in the muzzle)

* Signs of neurological problems (paralysis of the muzzle or tongue, a droopy ear, or drowsiness).

It is important to get veterinary help if you see any of the symptoms in one of your horses. Your vet can only offer supportive treatment, including anti-inflammatory medications. There is no cure.

Although the chance of contracting the disease yourself is small, remember to use insect repellant containing DEET when you're outside at daybreak and dusk.

Here are a few Web sites that have helpful information about WNV:

www.fightthebitecolorado.com/horses.ht

www.myhorsematters.com/ (American Ass'n of Equine Practitioners)

www.cvmbs.colostate.edu/aphi (Colorado State University's Animal Population Health Institute)

www.cdphe.state.co.us/dc/zoonosis/wnv/wnvhom.html (Colorado State Dept. of Public Health)

Article written by Erica Whitcombe

Thanks Erica!!!

Happy Riding!!!

Comments and feedback are always welcome!

Leslie @

Falcon Creek Farm

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