Gone are the days when you just grabbed a tube of whichever dewormer was on sale.
“We know now that the most effective deworming program involves treating the right horse at the right time for the right parasites,” says Bryant Craig, DVM, Merck Animal Health equine technical services veterinarian.
“This is a plan that controls parasites based on your horse’s needs rather than an arbitrary schedule and factors in where you live, the stocking density on your farm, whether you have a closed or open herd, and what dewormers you have been using.”
In most parts of the country, fall remains an important time of parasite transmission, which means it is when most deworming treatments should be administered. However, before you run out and pick up a tube of dewormer this fall, keep these important tips in mind:
Work with your veterinarian to use properly timed fecal tests to determine your horse’s shedding status (how much and of which parasites he’s shedding). Based on these results, your veterinarian will customize a deworming protocol for your horse. Some horses may require a more aggressive schedule than others.
In southern climates, mild winters also are conducive to parasite transmission. Periods of drought help control certain parasite populations (e.g., small strongyles) on pastures. In contrast, periods of unusually wet, warm weather are optimal conditions for parasite development.
Quarantine new horses to the farm, and check fecal egg counts. Use a larvicidal treatment to help limit the number and variety of parasites being introduced by the newcomer. This can be accomplished with larvicidal fenbendazole or moxidectin. Also, hold new arrivals in their stall for at least 72 hours after deworming before turning them out on pastures.
Quarantine is important to reduce internal and external parasite exposure to the resident population, and limit contamination of grazing areas.
Use a weight tape (or scale) to avoid under-dosing. Horses are generally heavier than you think.
“Elements of a successful deworming program include chemical and non-chemical parasite control strategies.” adds Dr. Craig. He encourages owners to ask their veterinarian for a parasite control visit to assess non-chemical parasite control strategies that could be employed on the farm.