Parasites are a constant problem in horses and can result in unthrifty condition, ulcers, respiratory problems, anemia, chronic colic and even death. With the development of de-worming products that can be given orally rather than by tubing, allowing more widespread and frequent use of de-wormers, parasite infection has diminished.
The pendulum has, however, swung, and wormers have unfortunately become too much of a good thing. Widespread use of wormers along with the infrequent introduction of new athelmintics has created parasites that are resistant to many of the drugs.
So how can horses become free of worms without constantly giving them drugs and creating resistant parasites? First, don’t worm indiscriminately. Have fecal counts done on horses before de-worming, and then decide if worming is needed.
Proper pasture management can help tremendously. Paddocks should be cleaned regularly, and pastures should not be overcrowded. If possible, feed hay in bunks or mangers rather than on the ground.
Grazing a cow or sheep with horses can make a big difference in parasite control. Since cows and sheep don’t share the same parasites as horses, they can eat the eggs or larvae of a horse parasite and break the life cycle of the parasite.
In addition, cattle and sheep graze the tall grass around manure piles that horses avoid. This grass helps protect parasites from heat and drying, shading them from direct sunlight and holding moisture. When the grass is grazed down, the parasites become exposed to the heat and drought, which kills them.
Using these techniques can help diminish a horses’ parasite load without overusing wormers. The end result is fewer drugs for the horse and fewer drug-resistant parasites.