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Tips to Protect Horses From Tick-Borne DiseasesBy Kentucky Equine Research Staff · July 18, 2017

Not all ticks are capable of transmitting Lyme disease to you or your horses. But why wait to see if those "tick-ing" time bombs are the “right” kind? Consider these four methods of protecting your horse against tick-borne diseases:

1. Avoidance. The black-legged (deer) tick is the only kind known to transmit Lyme disease. Those ticks are found in the Mid-Atlantic and northeastern United States, Minnesota, Wisconsin, and parts of California. Horses in those areas have high seroprevalence rates, indicating they have been exposed to the bacterium Borrelia burgdorferi that causes Lyme disease.

Ticks find a host through “questing,” which means they climb grass stems and perch on leaf edges with their front legs extended until a host brushes past them. It is therefore difficult to completely avoid tick exposure, but appropriate pasture maintenance can help.

“Insecticide sprays might be used, but many are not approved for use in horses and their efficacy against ticks has not been clearly demonstrated,” warns Bryan Waldridge, D.V.M., M.S., veterinarian at Kentucky Equine Research. “Anecdotal evidence suggests that long-acting canine tick sprays are safe and effective for reducing the number of live ticks on horses but are expensive.”

2. Removal. Daily tick checks should be performed to remove any attached ticks. Lyme disease is usually transmitted after the tick has been attached for 24–48 hours.

3. Vaccination. Although not approved for use in horses, a canine vaccine against Lyme disease is available and has been used to vaccinate horses in endemic areas, says Tom Divers, D.V.M., of Cornell University.

“Neither dose nor frequency of vaccination is established in the horse, but based on our previous research it is highly likely that horses with high OspA antibody [from vaccination] will be protected from infection,” Divers explains*.

4. Opossums. According to Rick Ostfeld, senior scientist at the Cary Institute of Ecosystem Studies, opossums are “remarkably efficient at eliminating foraging ticks” and are “unsung heroes in the Lyme disease epidemic.” Despite the tick-picking prowess of possums, equine experts do not advise horse owners to encourage opossums access to their premises.

“Opossums are known to excrete the protozoa responsible for equine protozoal myeloencephalitis, and owners are encouraged to practice appropriate property management to limit exposure of horses, hay, and feed to opossum feces,” advises Waldridge.

*Divers, T. 2013. Equine Lyme disease. Journal of  Equine Veterinary Science 33:488–492.