Controlling internal parasites, or worms, is an extremely important component of horse health care. Internal parasites are silent thieves and killers. The damage they cause often goes unnoticed until problems are severe.
Horse bot fly specimen
The most common and troublesome internal parasites in horses are roundworms, small and large strongyles, tapeworms and botfly larvae.
© 2015 by Janet Graham New window.
The most common and troublesome internal parasites in horses are roundworms, small and large strongyles, tapeworms and botfly larvae. Young horses are more likely to be adversely affected than adult horses.
All internal parasites have similar life cycles: Parasite eggs are passed in feces of infected horses; horses ingest parasite eggs or larvae from the environment; parasite larvae migrate through various tissues of the horse specific for each parasite and usually end up in the gastrointestinal tract, where they mature into adults.
Migrating larvae can cause tissue damage to the lungs, intestinal wall and blood vessels. The physical presence of the adult worm can cause intestinal irritation and intestinal obstruction and will take valuable nutrients away from the horse.
Unfortunately, there is no single parasite control program that suits all horses and all situations. You should consult your veterinarian to help devise a parasite control program for your horse or your farm.
In general, parasite control programs should include appropriate selection and use of anthelmintics, or dewormers, management practices that further reduce parasite transmission and evaluation of the control program.
The dewormer used must be highly effective against the parasite infesting your horse. Your veterinarian can help you determine which dewormer is appropriate for which horses. The correct amount of dewormer must be administered based on an accurate estimation of your horse’s weight; using a weight tape is strongly recommended.
Routine removal of feces from stalls, pastures and paddocks will decrease the number of parasite eggs/larvae in the environment. Manure should not be spread on pastures unless it has been properly composted for the appropriate amount of time.
True composting will kill internal parasite larva in approximately three months, while piling manure and letting it sit will take a year. The effectiveness of parasite control program should be evaluated once or twice yearly by having fecal examinations performed.
Press release by Cooperative Extension Service