Types of Horse Wormers

Colic is a major killer of horses, with intestinal parasites a prime cause of the condition. Since the introduction of easily administered paste, liquid, and pelleted wormers (deworming drugs) a generation ago, the incidence of colic has decreased dramatically. Deworming is vitally important for horse health, and you should consult with your veterinarian for advice on a deworming schedule for your animals.

  1. Ivermectin

    • While Equimectrin and Zimectrin are popular brands, ivermectin-based wormers have long been available in generic forms. Broad-based ivermectin kills most equine worms with the exception of tapeworms and small encysted strongyles. Praziquantel does kill tapeworms and is combined with ivermectin in the Zimectrin Gold and Equimax brands. Ivermectin is effective against bots, lungworms, roundworms, pinworms, neck thread worms, large-mouth stomach worms, and redworms. Ivermectin may be part of a rotational deworming schedule of different types of wormers, or it may be used exclusively every two months, as long as an ivermectin/praziquantel blend is administered at least once a year to kill tapeworms.

    Moxidectin

    • Moxidectin, sold under the brand name Quest, kills bot-fly and encysted small strongyle larvae. Unlike other commercial worming products, it has a very low overdose threshold, so it should not be given to foals or very old, sick, or debilitated horses. It is very important that moxidectin be dosed according to your horse's actual weight rather than his estimated weight. While other types of wormers may be doubled-dosed in certain protocols to get rid of particular types of worms, this should never be done with moxidectin. Compared to other wormers, moxidectin is effective for a longer time frame. Horses may be dosed every 12 weeks rather than every 8 weeks.

    Pyrantel pamoate

    • Pyrantel pamoate, sold under the brand name Strongid, is also available in generic forms. It controls and removes large and small strongyles, roundworms, and pinworms. Pyrantel pamoate may be given either in a dose syringe as part of a regular deworming rotation or in pelleted form daily. With a daily dose, larvae are continuously killed before they can do damage. Pyrantel pamoate has a high overdose threshold so you can double-dose by syringe annually to get rid of tapeworms. As it is ineffective against some types of worms, however, pyrantel pamoate should be used as part of a rotational deworming schedule.