Horse Side Vet Guide ®

Equine Health Resource

Manure has Grubs or Worms in It

Code Green - Contact Your Vet to Obtain Useful Advice & Resources

Code Green - Contact Your Vet to Obtain Useful Advice & Resources

  • If the results of the Whole Horse Exam (WHE) suggest the horse is otherwise normal.

Worms are frequently shed in manure after de-worming, and the number of worms seen roughly parallels the worm load that the horse was carrying prior to de-worming. If a horse had not been recently de-wormed, the presence of adult worms in the manure may (but not necessarily) mean that a horse has a severe worm infestation.

The most common parasite seen in manure are bot larvae (large, orange grub-like larvae). Large pale worms that looks like bean sprouts are usually Ascarid roundworms. Tiny thread-like worms may be small Strongyles. Many species are tiny and only seen with careful examination of the manure. Worms eggs are microscopic and can only be seen in laboratory examination.


Take a photo of the worms (with a reference like a quarter or dime for size), take a photo of your horse (for a body condition score), and share the photos with your vet. Sample manure from all your horses and submit them to your vet for Fecal Egg Count.


Your vet will evaluate this particular horse’s worming program and recommend that they examine a fecal sample. Fecal testing performed by your vet is recommended on a regular basis (usually twice a year) to determine whether your horse is in need of de-worming.

What Not To Do

Do not assume that if a horse has no visible worms in its manure, it does not have a significant worm infestation. Do not assume that if a horse has visible worms in its manure, that it has serious parasitic disease.

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

Author: Doug Thal DVM Dipl. ABVP


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