Ask the Expert: Coprophagia in Horses

Q: Sometimes I see my horse eating his own manure. Not only is it totally disgusting, but it can’t be good for him. I have heard horses do this when they are confined to a small pen and are bored, but he is in a bigger field, has grass to graze on and has a pasture pal, so I don’t understand why he is doing this. Is he lacking something? I try to keep the manure picked out but I can’t always keep up.

Q: Eating manure is a fairly common practice seen in foals but not so much in adult horses. The act of eating manure is called coprophagia, derived from the Greek “kopros” for feces and “phagein” for eat. No real studies have been done to determine exactly why adult horses do this, but there is little doubt that several factors will contribute: boredom, stress, or some dietary deficiency such as insufficient fiber and/or minerals.

A dietary deficiency can be addressed through consultation with your veterinarian and feed analysis of your pasture and hay. Make sure you also give your horse access to a plain salt block. You might also consider offering hay in the pasture so he has some other fiber source to grab his attention, especially if your pasture is sparse.

In regards to stress, it’s possible that your horse and his pasture partner are not as compatible as you might have thought at the beginning of their relationship. Other less obvious stresses might be best identified by an objective outsider, like your veterinarian, who can look carefully at your management setup and evaluate your horse’s exercise routine.

You seem to be doing the right things: offering grazing pasture along with companionship. Part of your horse’s current problem is that this behavior may have become a habit. And horse habits are often difficult to break. There really isn’t any harm in him eating manure other than the potential for consuming parasite larvae. The smart tactic here is for you to have your vet run fecal parasite egg counts twice a year and recommend a customized deworming plan to ensure that your horse’s parasite load is maintained below a threshold. Manure often contains a lot of undigested fiber and grains, as well as a bit of moisture—none of these components pose a hazard to his health.

Liked this article? Here are others you’ll enjoy:
Could My Horse’s Restricted Diet Cause a Vitamin Deficiency?
My Dog is Addicted to Eating Horse Manure

Nancy S. Loving, DVM, is a performance horse veterinarian based in Boulder, Colo., and is the author of All Horse Systems Go.

This article originally appeared in the December 2014 issue of Horse Illustrated. Click here to subscribe!