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Equine Health Resource

Intestinal Parasitism (in Adult)

Clinical parasitism can take many forms but what I am referring to here is signs of illness that are caused by the presence of parasites.

Intestinal parasitism is a common cause of weight loss, colic, diarrhea, and poor body condition in horses. It has been greatly reduced in the last 30 years due to improved dewormers and more frequent deworming. Unfortunately we are beginning to see resistance to dewormers and thus increased disease caused by worms. Due to this, the new approach to parasite control is fecal testing and targeted deworming.

Parasitism inhibits proper absorption of nutrients even if a horse’s diet is otherwise adequate, resulting in a dull or poor haircoat.


Incorporate fecal testing into your preventative healthcare regime, and use deworming pastes only as needed. Regular removal of manure from pastures can significantly reduce parasite burdens in horses. Proper composting of manure, in which the fermentation process kills parasite eggs, renders quality fertilizer that can be safely spread on pastures. Rotating pastures with other animals (cows, pigs or sheep) may also help reduce ingestion of strongyles by breaking the cyclical pattern of ingestion, infection and shedding. Likewise, annual or biannual cleaning of all barns, stalls, tack and equipment is good management that may help remove the more stubborn eggs that can survive for long periods awaiting a host.

Helpful Terms & Topics in HSVGWritten, Reviewed or Shared by Experts in Equine Health

Author: Doug Thal DVM Dipl. ABVP


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