Free Faecal Water Syndrome in UAE Horses: Is Timothy Hay a Contributing Factor?

Lately, I have noticed a recurring pattern in horses across the UAE: many develop free faecal water syndrome (FFWS) while being fed imported Timothy hay, and many improve once Timothy is removed from the diet.

By free faecal water syndrome, I mean the condition where horses pass normal or slightly soft manure balls, but water leaks separately before, during, or after defecation. It is not true diarrhea, yet it can be frustrating for owners and uncomfortable for horses.

What interests me is that this is not limited to one discipline or type of horse. I have seen it in polo horses, sport horses, racehorses, and leisure horses. While not every horse fed Timothy develops the problem, the frequency with which it occurs makes me believe there is a connection worth exploring.

Is Timothy Hay Damaging the Colon?

Based on my observations and the research currently available, I do not believe Timothy hay directly damages the lining of the large intestine. Most horses with free faecal water show no signs of severe inflammation, ulceration, or destruction of the colon wall. They often maintain body condition, appear healthy, and have normal blood work.

Instead, I suspect the issue is related to how Timothy hay affects hindgut fermentation and water regulation within the large intestine.

The Role of the Hindgut

The horse’s cecum and large colon contain billions of microorganisms that ferment fibre. These microbes produce substances that nourish the intestinal lining, support the mucus barrier, regulate water absorption, and help maintain normal manure consistency.

When fermentation patterns change, water handling within the hindgut can change as well.

In many affected horses, the manure balls remain formed while water separates from the faecal mass. This suggests that the problem may be less about excessive fluid production and more about the inability of the intestinal contents to retain water effectively.

Why Timothy Hay May Be a Trigger

Not all Timothy hay is the same. Quality can vary depending on harvest maturity, fibre levels, leaf-to-stem ratio, storage conditions, and transport.

Most Timothy hay fed in the UAE is imported and has often undergone harvesting, compression, shipping, container transport, and extended storage before reaching the horse. These factors can influence fibre digestibility and fermentation characteristics.

Timothy is also a cool-season grass developed for temperate climates. Compared with many mixed meadow hays, it often contains more structural fibre and coarser stems, especially when harvested late. In susceptible horses, this may contribute to altered microbial fermentation, reduced water retention within the fibre matrix, and separation of water from the faecal mass.

The Sand Factor in UAE Horses

Living in the UAE, it is impossible to ignore the role of sand.

Most horses here likely carry some degree of sand burden, even when owners are diligent about feeding psyllium regularly and other methods to reduce sand intake. While sand may not be the primary cause, it could make the hindgut more sensitive to dietary changes.

A horse with a perfectly healthy colon may tolerate Timothy hay well, while a horse with mild chronic irritation from sand may develop free faecal water on the same forage.

This leads me to wonder whether the equation is often:

Timothy hay + mild chronic sand burden + hindgut sensitivity = free faecal water

Rather than Timothy hay alone being responsible.

The Mucus Layer: A Missing Piece of the Puzzle?

One area that I believe deserves far more attention is the mucus barrier of the large intestine.

The colon lining is covered by a protective mucus layer produced by specialised cells called goblet cells. This mucus is not simply a slippery coating. It is a highly sophisticated biological barrier that plays a vital role in maintaining intestinal health.

Functions of the Intestinal Mucus Barrier

The mucus layer serves several important functions:

• Protects the intestinal wall from mechanical damage.
• Prevents harmful bacteria from attaching directly to intestinal cells.
• Helps regulate water movement within the colon.
• Supports beneficial microbial populations.
• Acts as an interface between the microbiome and the immune system.

The Importance of Butyrate in Colon Health

A healthy mucus layer depends heavily on the activity of the hindgut microbiome. As microbes ferment fibre, they produce short-chain fatty acids, particularly butyrate. Butyrate is a major energy source for the cells lining the colon and is essential for maintaining a healthy mucus barrier.

It supports mucus production, strengthens the intestinal lining, and helps maintain the tight junctions that regulate what passes across the gut wall.

In a healthy horse, there is a continuous cycle:

Good fibre fermentation → adequate butyrate production → healthy mucus layer → proper water regulation and intestinal function

How Changes in Fermentation May Affect Water Regulation

However, if fermentation patterns become less favourable, this balance may be disrupted.

Reduced butyrate production may lead to:

• Thinner or less effective mucus.
• Altered water regulation.
• Increased sensitivity of the intestinal lining.
• Changes in intestinal motility.
• Reduced ability of manure to retain water.

Importantly, this does not necessarily result in obvious disease. The horse may still maintain weight, appear healthy, and produce normal manure balls.

Instead, the colon may simply lose some of its ability to keep water incorporated within the fibre matrix of the manure. Water then separates from the faecal mass and is expelled independently, producing the characteristic signs of free faecal water syndrome.

This is one reason why I am not convinced that Timothy hay directly damages the intestinal lining. Rather, I suspect that in susceptible horses, certain forage characteristics may alter microbial fermentation patterns, which then influence mucus production and water regulation.

The situation may be particularly relevant in the UAE. Chronic low-level sand exposure may create subtle irritation of the intestinal environment, making the mucus barrier less resilient. A horse with an already challenged mucus layer may be less able to adapt to changes in forage quality or fibre characteristics.

Why Horses Improve When Timothy Hay Is Removed

The strongest evidence, in my opinion, comes from the horses themselves.

Repeatedly, I have seen horses improve when switched from Timothy hay to alternatives such as mixed meadow hay, mixed grass hay, Rhodes grass, or carefully balanced grass combinations.

Whether this is due to the fibre profile, fermentation characteristics, maturity of the hay, storage conditions, or a combination of factors remains unclear. However, the clinical response is difficult to ignore.

The fact that many horses also respond to management strategies aimed at supporting hindgut health further strengthens the theory that the problem lies within the interaction between forage, microbes, and the mucus barrier rather than structural damage to the intestine itself.

Final Thoughts on Timothy Hay and Free Faecal Water Syndrome

My suspicion is that free faecal water syndrome may not simply be a manure consistency problem. It may be a visible sign that the delicate relationship between forage, the hindgut microbiome, the mucus barrier, and water regulation has become disrupted.

While more research is needed, understanding this relationship may ultimately help us explain why so many horses improve when Timothy hay is replaced and why maintaining a healthy hindgut ecosystem remains one of the most important aspects of equine digestive health.