What is the best method for their control? There are several non-medical ways to control internal parasites in horses. The number one war tactic is periodic removal of manure from pasture! If we simply remove the feces from grazing areas, the worm population in horses decreases dramatically. Otherwise, horses should be dewormed a minimum of every 8 weeks, 6 weeks prefered, 4 weeks in barns that have a quick turn over.

Think you know all about worms and deworming? Take this simple true/false test:

Rotating dewormers has been proven to be almost unnecessary since the implication of Ivermectin. This is due to the fact that after 12 years of use, no reported cases of resistance to Ivermectin have developed. The best method is to schedule dewormers so that the best results will follow. Dewormers are now designed in such a way that an exaggerated dose must be given to truely harm a horse. This is done with saftey in mind for "accidents." For some dewormers (like Ivermectin) almost 10 doses are needed before causing damage to a horse. However, with large infestations of worms in a specific horse, overdosing can cause impaction colic. Less than the recommended dose can help parasites develop a resistance to the wormer, so it is almost better to overdose than under. Although Ivermectin is a broad spectrum killer, it does NOT kill Tapeworms. Tapeworms in horses used to be a very minute problem. Since the development of Ivermectin, large Tapeworm infestations have been on the rise. As the Tapeworm has no competitors within the digestive tract, they can take over.

So what's the strategy? The most effective schedule involves Ivermectin as the key player in a deworming schedule. Ivermectin is sold under many brand names such as Zimectrin, and Rotectrin 1. Strongid in a double dose is the best method for eliminating the Tapeworm problem. Here's a sample 8-week deworming schedule: