If you read the title of this article and said, "WHAT?!?" don’t worry–you’re not alone! No horse owner wants to think of even a single worm burrowing in their horse’s innards. But a goal of zero tolerance for worms is no longer a realistic one; increasing resistance of worms (particularly small strongyles) to common deworming drugs means we have to use much less of them to avoid creating even more resistant superworms.

At the 2009 American Association of Equine Practitioners Convention, held Dec. 5-9 in Las Vegas, Nev., Craig R. Reinemeyer, DVM, PhD, president of East Tennessee Clinical Research, discussed the current state of equine internal parasite resistance (primarily in small strongyles) and the new strategies we must use to control it. The basic idea is that we need to use dewormers far less often and more selectively to preserve their value and, yes, even learn to live with the worms to some degree.

Tip #1: Stop Focusing on the Wrong Things

"’Deworming’ as a component of a control program is an unfortunate term, because it emphasizes treatment rather than prevention," noted Reinemeyer. While we tend to think parasite control efforts focus on killing adult worms present in our horses, he says that this is entirely the wrong goal. Our objective should be to maximize the health of our horses, and most worms do their worst within a horse as immature larvae. Thus, the better goal is to reduce parasite reproduction and contamination of the environment, so there are fewer worm larvae in the next generation to damage our horses