In line with our continued discussion of basic vaccinations and horse health upkeep, I wanted to complete our discussion of what we consider “core” vaccines. Core vaccines are those that every equine (and equid for that matter!) should receive – they include EWT, Rabies, and West Nile Virus. We will continue our blogs with discussion of diseases whose vaccines are not considered part of a core program. Today, we will close with the newest member of the core group – West Nile Virus.
West Nile Virus (WNV), like EEE and WEE, causes encephalitis (inflammation of the central nervous system) and results in neurological symptoms. Humans and other species can acquire this disease as well. West Nile was not found in the United States prior to its introduction to New York in 1999. Clinical signs usually progress back-to-front, meaning the hind-limbs are often affected first, then the forelimbs and so on forward. Early symptoms include inappetance, fever, hind-limb weakness and ataxia. Often the muscles of the muzzle twitch erratically, and they become hyper-excitable. Many horses with West Nile Virus are seen in a dog-sitting position early in the course of the disease, and it progresses to recumbency (lying down) and death. Other neurological signs seen with WNV include blindness, difficulty swallowing, head pressing, seizures, and aimless wandering.
Like EEE, birds keep the source of West Nile Virus alive in the United States, and mosquitoes feeding on the infected birds are the vectors that transmit it to the horse. There is no specific treatment for West Nile, other than supportive care for vital body functions. Recumbent horses must be supported in a sling or turned over every four hours until recovery occurs (if it does). Like with other neurological diseases, when the horse becomes recumbent, euthanasia is generally recommended. Vaccination is recommended once yearly, but it is not a guarantee against infection. The goal of vaccination is to reduce the likelihood of infection, and minimize the clinical signs should infection occur. It is also crucial that you do your part in minimizing mosquito exposure for you and your horse!
You can minimize mosquito populations on your property by eliminating sources of stagnant water (or stocking them with fish), and cleaning out your clogged gutters! Mosquitoes breed in any puddle that is left for more than four days. Keep your barn lights out at night – mosquitoes are attracted by yellow incandescent bulbs. Placing these bulbs at sites away from your barn can draw them away from your horses. Report any dead birds you find on your property to the Alachua County Health Department (DO NOT pick up a carcass without gloves!), and eliminate roosting areas in your barn.
As you are probably wondering, my foot is doing well – the atrophied muscles are starting to come back and my limp is almost gone! I can’t tell you how wonderful it is to be prowling around the office again, inspecting your trailers and your horses. And it was fortunate my recovery happened at such an opportune moment – there’s a new stray lurking around the office that I must defend against! Have a Happy Valentine’s Day, and we hope you can make it to our Senior Horse Seminar this Thursday at 6PM at Canterbury! May your litter box be clean and your food bowl full!