For decades an array of anthelmintics have kept equine parasites under control. But the increase in resistance issues have made it clear that that effective parasite control requires more targeted administration of dewormers. Broader management measures are also necessary. As your horse ages it becomes increasingly important to take a holistic approach to parasite control. Ask your veterinarian to devise a customized deworming program for your horse and complement it with commonsense management practices.

Manage to optimize parasite control

• Manure removal. Keep your horse’s stall, paddock and pastures as clean as possible. Removing manure interrupts the life cycle of most parasites. Consider composting manure or pay to have it hauled away. If you choose to spread manure, do so with parasite prevention in mind. Spread no more than your pasture can reasonably take up in nutrients and keep horses off pastures for a day or so. Never spread manure on a wet pasture or if rain is in the forecast.  

• Pasture management. If your pasture is too large to pick up manure routinely, frequent mowing and harrowing will break up the manure balls and kill eggs and parasite larvae by exposing them to air and sunlight. Also, avoid overcrowding your turnouts, which can force horses to graze near soiled areas. Provide hay in raised feeders so horses will not have to eat off the ground, and make sure water remains clean and well away from manure accumulations.

• Fecal egg counts. Simple laboratory tests for the quantity and type of eggs present in a horse’s manure, fecal egg counts can help determine when it’s time to administer a dewormer and which one will be most effective. A follow-up count done 10 to 14 days later will tell you how well your treatment worked. If there’s a 90 percent reduction in parasite eggs, the deworming treatment was effective. If not, you’ll need to try another anthelmintic.