Question: My 16-year-old gelding has very soft manure. It’s almost diarrhea, but not quite that bad. I purchased him from a lesson program and initially thought his manure was a result of the stress of that situation. But he’s been at my quiet home barn for a year now and his manure has the same consistency. He’s on a primarily hay (orchard grass) diet, with only a half-scoop of grain twice a day. In the summer he has full-time access to pasture, but the grass isn’t very lush. My veterinarian has found no infection, parasite issues nor any indication of digestive problems. We did a “float” test for fecal sand, and he appears to be fine in that regard. His manure is the same year-round. Is there anything else I should investigate? Might a change in feed firm up his manure? His hind end and tail are always filthy.

Answer: It’s understandable that you’re concerned about your gelding’s consistently soft and watery manure, especially after a year of living in a calm environment with a stable diet. Given that your veterinarian has ruled out more serious issues like infections or colic, let’s dive into what else might be causing this problem and explore some changes you can make to help firm up your horse’s manure. We suggest focusing on the following three areas.

Diet

In our experience, some cases of persistently soft stool improve with a change in dietary hay. Some horses seem to have varying tolerances for the sugars—particularly water-soluble carbohydrates (WSC)—found  in particular types of hay, and this can influence the consistency of their feces. Common culprits are perennial ryegrass and orchardgrass. To address these problems, we suggest switching to good quality, first-cut meadow hay, a mixture of leafy grasses and clover. Meadow hay typically has a much lower WSC content, but we would suggest confirming this with a laboratory analysis. Of course, as with any change in a horse’s diet, you’ll want to make any forage switch gradually.

Gut health

 The bacterial populations living in your horse’s gut play a huge role in digestion. If the gut flora is unbalanced—maybe from stress or previous dietary changes—it can lead to ongoing issues like persistently soft manure. A microbiome analysis can help to identify any imbalances. Ask your veterinarian to direct you to a laboratory or company that can do this analysis.

Probiotics and prebiotics

 Supplements that support gut health might be just what your horse needs. Look for probiotics that contain Saccharomyces cerevisiae or boulardii, organisms that have been shown to help horses with similar issues. It’s important, however, to avoid probiotics that are high in sugars.

Your gelding’s soft manure might be frustrating, but with some dietary tweaks and gut support, there’s a good chance you can get things back to normal. Focus on changing his hay, adding a gut-friendly probiotic, and avoiding feeds that are high in sugar. Regular veterinary checkups and fecal tests will also help ensure you’re on the right track.

Tommaso Danese, DVM
University of Parma
Parma, Italy

Emanuela Valle, DVM, PhD
University of Turin
Turin, Italy