Internal parasites are insidious culprits. They steal, damage, and even kill. The worst part of the whole scenario is that they can’t be totally eliminated, only controlled. In the theft department, internal parasites rob in two ways: First, they steal nutrients from the horse’s body; second, they take money from the owner’s pocket in the form of lost food value. Adding to the problem is the fact that there are many types of parasites, and each seems to have its own unique way of attacking its host–your horse.

It is estimated that more than 150 internal parasites afflict horses, according to an American Association of Equine Practitioners (AAEP) informational brochure that was funded by Bayer. Some parasite species, the report stated, can lay more than 200,000 eggs per day, so it is readily apparent that parasite loads can escalate quickly.

The good news is that scientific research has been successful in developing dewormers that are effective if used properly. There also has been improvement in administration of the dewormers. In days gone by, there were two basic ways to get the dewormer into the horse’s body–via tube deworming or ingestion with feed.

Obviously, administering the dewormer with a nasogastric tube was the most effective because then one could be certain that the entire dose went into the horse’s body. However, this method required the services of a veterinarian. Dewormers in powdered form were also effective, but sometimes horses found them unpalatable and simply wouldn’t eat them