With summer comes ticks. Ticks are usually found in the horse’s mane and tail, but they may attach anywhere on the body. The longer hairs on the back of the fetlock are another favorite spot.
Tick bites can cause nasty skin reactions, often with a secondary infection. Usually, by the time the bite is discovered, horses have large weeping, crusty areas in the mane that eventually cause hair loss as well.
We all know ticks also carry disease, including Lyme disease, blood-attacking spirochete organisms such as babesia or ehrlichia, and encephalitis viruses, possibly including the West Nile virus (see March 2000).
Ticks seem to be everywhere. Simply riding through a wooded area can result in many ticks, especially if you have to duck a branch or two to get where you’re going. Even horses pastured in cleared fields adjacent to wooded areas often get infested.
Tick dips, sprays and powders sold for use in other species are NOT necessarily safe for use on horses, and many of the common fly-repellent sprays for horses have low efficacy against ticks. Your best bet, if you’re in a heavy tick area, is to look for one that specifically states it will repel ticks. Synthetic pyrethrins, such as resmetrin and cypermethrin, are more effective than the natural pyrethrins. Natural pyrethrins are only effective in high concentrations (products identified as “concentrated”). Other natural repellents, such as citronella, are not scientifically proven to be very effective.
Appropriate equine products include Farnam’s Flysect Super C, Tri-Tec 14, Repel-X Ready-To-Use, Repel-X Lotion, and Bite-Free, as well as Fearing’s Poridon. Even with these products, however, it’s unrealistic to expect 100% protection.
Your best defense is to meticulously check on a daily basis for attached ticks. Make it part of your daily grooming process. Getting those ticks off within 24 hours of a bite lessens the chances of the spread of disease. To remove a tick, place tweezers as close to the skin as possible, grasp the tick firmly and pull. Heads/mouth parts are rarely left behind. Should this happen, however, use the tweezers to pull out the remaining parts.
Note: There is a common belief that ticks were the vector for Potomac horse fever, and one of the reasons it’s been brought under control was ivermectin, which somehow prevented ticks from taking hold when they bit a horse.
It’s true that studies in cattle, goats and deer have shown that a single oral dose of ivermectin (such as would be given to deworm a horse) can either kill or sterilize some biting flies and ticks if they attach and feed after the treatment. The effect is greatest for the first 24 hours after treatment but reduced reproductive capacity in the insects could occur for up to 30 days. However, it does NOT prevent them from biting and feeding. Ticks may not become as engorged as they normally would, but they are attached. Improvement in Potomac horse fever infection rates would be considered indirect, basically due to eventually decreasing the number of biting insects around.
However, the method of transmission of Potomac horse fever is far from clear. One experiment exposed susceptible horses to over 500 ticks carrying the organism but none became ill. (When injected with it after the experiment, all the horses became ill.) Both biting flies and ticks are suspected to transmit Potomac horse fever, but the manure from infected horses also contains the organism, and spread by exposure to the organism when grazing is also a possibility.