In recent years there has been a shift in deworming recommendations. In the past, veterinarians used to develop a rotational schedule using the different products available, and horses were given deworming every 2-3 months. What we have discovered is that this system is a overuse of deworming products for most horses, and it was helping to develop resistance in the parasite populations.
What we recommend now is a Fecal Egg Count, which is a simple test on the manure to determine each horse’s parasite burden. This test costs $20, and should be done on every horse on the farm BEFORE they are dewormed. With the results of this test, we can develop a deworming program that will be specific to each horse. We recommend fecal egg counts 3-6 times per year, and deworming can be done as little a twice yearly (up to 5 times yearly) depending on each horse’s need.
To collect a fecal sample: collect 1-2 balls of fresh manure in a plastic baggie. Remove as much air as possible, and seal the baggie. Keep refrigerated until you can drop it off at the clinic (or have the veterinarian pick it up during an appointment). Be prepared to tell us the last time you dewormed, and with what product. Unless we are testing for resistance, the fecal should be at least 4-6 weeks after administration of Panacur (Fenbendazole) or Strongid (Pyrantel), at least 6-8 weeks after administration of Zimectrin (Ivermectin) and at least 12 weeks after administration of Quest (Moxidectin).