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Equine Health Resource

Fecal Exam for Parasites, Egg Count



Adult intestinal parasites shed eggs into the equine intestine, which appear in a horse’s manure. These eggs develop into larvae in the manure and are ingested again, where they complete their life cycle within the horse.

Fecal examination for parasites helps quantify the worm load a give horse has by counting the number of eggs per unit manure.

A second test, known as a fecal egg count reduction test (FECRT), is performed 2 weeks after worming and tests the effectiveness of the worming compound against the parasites.

Your role is to properly collect, label and submit manure samples to your vet. Manure samples must be fresh, packaged in a plastic bag with the air pushed out of it, and stored in a refrigerator for no more than 12 hours before submission to your vet.

There are a number of different methods for performing the examination but the basic concept is this: most parasite eggs will float when mixed into a concentrated salt solution. Manure is mixed with such a solution, causing the eggs to float to the top. They are collected from the film on top of the liquid, and using a microscope, they are identified and counted.

This diagnostic can be performed at any time of the year, however it must be at least 8 weeks after last deworming, and 12 weeks after deworming with moxidectin (Quest) products.

A reasonable approach is to schedule this testing between your chosen worming times. For example, if you deworm your horse(s) in March and November, a mid summer fecal examination would help determine the need for a third de-worming during the summer.

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


  • Does the fact that the exam was negative mean that the horse has no parasites?
  • Author: Doug Thal DVM Dipl. ABVP


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