By Sarah Welk Baynum
Fecal water syndrome in horses (FWS), also known as Free Fecal Water Syndrome, can be frustrating for horse owners because of the symptoms and so many unknowns this syndrome brings.
While studies have helped rule out what does and doesn’t cause Fecal Water Syndrome, there are still many variables that could play a part in a horse being affected by it.
Fortunately, there are some things horse owners can do to try and help alleviate these uncomfortable symptoms. In this article, you’ll gain a better understanding of what we know about Fecal Water Syndrome, its symptoms, what could make horses prone to it, and tips for treating and preventing FWS.
Understanding What Fecal Water Syndrome Is and What Causes It
While Fecal Water Syndrome can easily be confused with diarrhea, they are not the same issue. With diarrhea, the manure itself will be more liquid in consistency than usual versus the way feces are expelled in phases with FWS.
The manure from horses with Fecal Water Syndrome is expelled in two phases—a solid phase and a liquid phase. Compared to normal horses, whose feces are expelled in one phase, typically with a solid pile of manure.
Horses with FWS will have manure expelled in a normal consistency in phase one or two, but then also expel fecal water in another phase. The phases of how manure is expelled in horses with FWS can be in either order.
Fecal water will oftentimes be expelled directly after more solid manure, but some horses will expel fecal water before, during, or after the passing of manure. Sometimes, just fecal water by itself is expelled.
Unfortunately, the causes of Fecal Water Syndrome are still not completely known, although research has helped rule out what might or might not cause this issue. This is part of what makes this syndrome so frustrating for horse owners, since there is so much unknown when it comes to the mechanics behind it.
Symptoms of Fecal Water Syndrome
As previously mentioned, the feces will be specifically expelled in a way that is distinct in those two phases, and different than regular defecation or even diarrhea. However, horses with Fecal Water Syndrome do not display any other outward symptoms or show signs of illness other than the way their manure is expelled.
Unfortunately, this syndrome can cause quite a mess on the horse’s hind end. A tell-tale sign of fecal water syndrome other than the way it’s expelled is the way it coats the tail and hind legs of the horse. This feces coating can cause skin irritation, made worse by flies being drawn to the horse’s rear end due to the smell.
What Recent Studies Say About Fecal Water Syndrome
Recent research studies help us understand what might and might not cause FWS.
One study that has explored Fecal Water Syndrome investigated whether there's a difference in the microbiota between those with FWS and healthy horses. Unfortunately, there was no significant difference in the microbiome of horses with fecal water syndrome versus those without.
In fact, one study even took a much different approach, performing a fecal transplant. This involves taking manure from healthy horses who did not have FWS, blending it with saline, and using a tube to perform the transplant into the digestive tract of a horse with Fecal Water Syndrome. This method can be helpful when handling hindgut issues in horses. However, in this instance, the microbiota did not change, and no other long-term changes were noted in horses with FWS.
Another study looked at the composition of the manure in horses with Fecal Water Syndrome and compared it with a healthy horse’s manure. The theory was that there was an unhealthy shift in the microbial population that lived in the hindgut, which might be a cause of FWS. They observed the total short-chain fatty acids produced after it was broken down in the hindgut. This helped them identify what the fermentation in the hindgut was like in healthy horses versus those with Fecal Water Syndrome.
Interestingly, the results were almost exactly the same. The total short-chain fatty acids and the pH are extremely similar. In this particular study, lactic acid was similar, if not lower, in horses with FWS. This suggests it isn't a case of hindgut acidosis. From a research perspective, this points to no difference in the microbiome with what we can measure with the technology we have today.
Studies have also ruled out poor dental health and high parasite loads as a contributing cause of horses developing Fecal Water Syndrome.
What we do know is that FWS has been reported in many horse breeds, so it isn’t breed specific, and is more common in the winter.
The increased occurrence of FWS in the winter, which tends to resolve during the summer months, suggests that the composition of forage (grass versus hay) may play a role in the development of FWS in some horses. However, more research is necessary to fully understand this relationship.
Horses were also found to be more likely to have FWS if they have a low social rank in the herd, and geldings were at greater risk of having FWS than mares. Mares may be at lower risk because they are often higher in social rank than geldings, though.
Treating and Preventing Fecal Water Syndrome
Because there is still so much unknown about the cause of Fecal Water Syndrome, there is no single strategy to help horses with FWS.
Since social hierarchy can be a potential cause, moving a horse with FWS to a pasture with a different group of horses is worth trying.
A horse’s hind end is coated in feces with Fecal Water Syndrome, so frequent baths of the affected area will help with fly control and keeping the skin from being negatively affected by the feces.
Nutrition, and the type of forage the horse consumes, can potentially help treat and prevent future bouts of Fecal Water Syndrome. Because the “stemminess” of certain types of hay could be a factor contributing to FWS, a diet of softer, easier to digest hay or grasses might help alleviate FWS in some horses.
A diet low in sugars and starches (NSC) with a higher daily intake of protein and fiber has also been shown to help horses with FWS. A pelleted feed, like Kalm ‘N EZ®, fits this description perfectly and would be highly recommended for horses with Fecal Water Syndrome.
Some horses with FWS have also responded well to Constant Comfort Plus®, as this helps ease any underlying gastro-intestinal issues.
Need help with a diet plan for a horse with Fecal Water Syndrome? Our equine team would be happy to help you with a personalized feeding plan!