Recommended Worming Routine
Get off to the Right Start
_{by Linsey McLean}

Worm eggs that are ingested from pastures hatch quickly and perforate the intestinal lining. They then begin a long-term migration through body tissues and organs, where they do their greatest damage. This migration can take 10 to 12 months as they grow and develop. They can migrate anywhere, even through the brain, heart, lungs, etc. Close to maturity, these worms migrate toward the intestine again, with many reentering through the mesenteric artery, which feeds the intestine. This perforation can cause clots and blood flow blockage, resulting in colic and gastrointestinal distress.

Larvae then finish their maturation in the intestine for another 18 to 30 days, and begin laying eggs on their own, thus perpetuating the cycle. Worms are generally only susceptible to worming agents when they are in the intestine, only after doing their damage during migration. They continually enter the intestine from body tissues, so worming for one day is only effective that day. By the next day, another batch will have entered, after the worming drug has passed through the gut and been eliminated.

Wormers are "pass through" kill. Fortunately, the larvae maturation period serves as a treatment window, since they will not be ready to lay eggs for another several weeks to a month. This is why we can come back in a month with another dose of wormer.

With the following wormer rotation program, the best use of chemical classes is used to kill off intestinal worms at the optimum time. Worm every 30 days. It's easy to remember if you think of worming with paying bills on the first of each month. Mark your calendar!

1.) A triple dose by the horse's weight of Pyrantel Pamoate known as Strongid^® Paste - NOT Strongid C (another formula). This will get tape worms that are not targeted by any other wormer.

2.) Anthelcide EQ^® at 1 1/2 to 2 times dose per weight (per package instructions to kill Strongiloides species).

3.) Ivermectin as either Zimectrin^® or Eqvalaan^® (same drug, same dose). REPEAT CYCLE, alternating Quest® for Ivermectin.

Continue to REPEAT CYCLE, alternating Ivermectin and Quest^® for Step 3.

NOTE: If horses are maintained in a relatively clean environment, manure picked up or plowed under, pastures rotated, not overgrazed or overcrowded etc, then the worming recommendations can be extended to two months between wormings, but the rotation schedule and doses will still be the same.

Be sure to check out our FAQ's on Worming