🚫 Vet Guide 2025: Free Fecal Water Syndrome in Horses Isn’t Diarrhea 🐴💧

Author: Dr Duncan Houston, BVSc

It’s messy, frustrating, and often mistaken for diarrhea—but free fecal water syndrome (FFWS) is a separate and poorly understood condition in horses. With FFWS, horses pass normal manure along with dribbles of watery fecal fluid. While not life-threatening, the condition can cause skin irritation, attract flies, and complicate daily management. In this 2025 article, Dr Duncan Houston breaks down what FFWS is—and isn’t—and what we currently know about causes and care. 🐎🧼

💧 What Is Free Fecal Water Syndrome?

FFWS is not diarrhea. With diarrhea, the entire stool is loose or watery. In contrast, FFWS involves:

• 💩 Normal-formed manure
• 🌊 Thin fecal water passed before, during, or after defecation
• 🧼 Contamination of the tail, legs, and hindquarters

This water is enough to stain, irritate, and attract flies, especially in horses with long tails or feathers. 🦟

🧪 What Causes Free Fecal Water?

The short answer: We’re not sure. Many theories have been proposed over the years, including:

• 🌿 Feeding alfalfa hay or haylage
• 💧 Drinking very cold water
• 🦷 Dental problems
• 🧫 Parasites or gut infections

However, studies have failed to link these factors directly to FFWS. ❌

🧠 What the Research Suggests

A study from Germany uncovered interesting behavioral and environmental correlations:

• ⚠️ More common in low-ranking horses in herd environments
• ❄️ Worse in winter, likely due to confinement and stress
• 🧑‍🤝‍🧑 Social stress and anxiety may play a role

Notably:

• 🧑‍🔧 Dental disease, parasites, and cold water were NOT linked to FFWS
• 🐴 Geldings are more affected than mares
• 🎨 Paint horses may be more predisposed

🔍 Key Differences Between FFWS and Diarrhea

🧼 Management Tips for FFWS

• 🐴 Reduce herd stress—separate subordinate horses if needed
• 🌱 Switch to grass hay or different forage to test sensitivity
• 🧼 Clean tail and legs daily—apply barrier creams to protect skin
• 🧠 Add gut-friendly feeds—low-starch, high-fiber rations

⚠️ Avoid overusing supplements. Many products claim to "solve" FFWS, but few are supported by science. Always consult your vet. 💊

🧠 Dr Duncan Houston’s Advice

"If your horse’s stool is normal but their tail is a mess, you're likely dealing with free fecal water—not true diarrhea. Focus on stress, social hierarchy, and gut balance." 🐴💬

📋 When to Call Your Vet

• 📉 If your horse has weight loss, pain, or fever
• 🩺 If fecal water becomes persistent or worsens
• 🧪 If you suspect a parasite or dental issue

🔚 Final Thoughts: Manage, Don’t Medicate Blindly

Free fecal water syndrome is manageable, even if the exact cause isn’t clear. With a calm environment, consistent feeding, and basic hygiene, most horses improve. 🐎❤️

Need help managing your horse’s gut health or behavior? Visit AskAVet.com or download the Ask A Vet app for 24/7 vet-backed advice. 📱💧