If you’re brushing your horse and notice a wet manure along the legs and tail, you may wonder what’s going on. Even when the manure in the stall looks normal, the hind limbs can still be damp, stained, and irritated. This pattern points to a condition known as Fecal Water Syndrome (FWS). It’s not the same as diarrhea, and recognizing the difference is key to addressing it effectively.
Is It Diarrhea or FWS?
With diarrhea, the entire bowel movement is liquid or highly loose, often described as a“cow-pie” stool. Affected horses are lethargic, depressed, feverish, off feed or show signs of systemic illness. It’s usually a sign of infection, inflammation, or another serious underlying problem.
With Fecal Water Syndrome (FWS) the manure has normal balls followed by or accompanied by a stream of dirty water that runs down the hindquarters. It’s a mechanical issue—water isn’t being absorbed properly in the hindgut—rather than a systemic disease. The horse often looks and behaves normally. They eat and drink well and are active and engaged.
What Causes FWS?
FWS can arise from a variety of factors such as diet change, social or environmental stress, dental issues or even parasites or sand consumption.
With diet changes, a sudden switch to rich forage (for example, moving from grass hay to alfalfa) can disrupt hindgut water absorption. Social and environmental stress such as moving a submissive horse into a new herd where competition for the feeder is intense—can trigger FWS. If a horse can’t effectively chew long-stem fibers due to a dental issue, larger feed particles may irritate the gut lining, reducing water absorption in the hindgut.
Managing and Treating FWS
The best approach to FWS is a combination of preventative management, symptom care, and veterinary guidance. Here are steps to help with FWS.
1) Cleanliness and skin protection
The liquid portion can be caustic and may irritate or scald the skin. Wash affected areas gently with mild soap and warm water. After cleaning apply a barrier cream such as petroleum jelly or zinc oxide to help shield the skin from irritation.
2) Dietary and feeding adjustments
Reduce or temporarily remove rich grains, concentrate feeds, and high-sugar supplements. Emphasize high-fiber, easily digestible forage and access to clean water. Probiotics or prebiotics can help hindgut bacteria and overall gut health. ¼ cup of Chia seeds given every 12-24 hours can help.
3) Stress and social dynamics
If social stress is implicated, adjusting turnout groups or feeding arrangements can resolve symptoms relatively quickly.
4) Veterinary evaluation
Involve a veterinarian to rule out parasites or sand accumulation in the hindgut.
Fecal Water Syndrome in horses is a condition where normal solid manure is followed by or accompanied by a stream of liquid fecal water. It’s typically a mechanical issue related to hindgut water absorption and is often driven by management, diet, and stress. While veterinary advice remains essential to exclude other conditions, many cases improve with dietary adjustments, stress reduction, and proactive stall and turnout management.