Q. For the last several months my horse has had chronic loose stools. I had the vet out and she has investigated but can’t find anything wrong. She’s suggested that, because my horse is otherwise healthy, I shouldn’t worry about it. However, I can’t help but think there’s something wrong. Plus, the loose manure coats my horse’s legs and is irritating his skin. I’ve tried most of the probiotics available at my feedstore with no impact. Do you have any suggestions?
A. Chronic loose manure or passing water after manure is an issue horse owners often ask me about. It appears to be a condition that plagues many horses and is certainly distressing to owners. My first recommendation is always to have your vet examine the horse to rule out issues such as sand in the large colon or internal parasites, which can cause loose manure, as well as pathogenic (disease-causing) bacteria such as salmonella.
Assuming the horse has an otherwise clean bill of health, I do have a few things I typically try and that often help. Which I try first depends on the horse’s history and the information the person managing the horse provides me with.
Research has shown live Saccharomyces cerevisiae yeast helps stabilize the horse’s hindgut environment. Despite being live, it’s considered to be a prebiotic rather than a probiotic because it doesn’t reach the intestinal tract in a viable state. It also doesn’t directly influence the horse’s health and well-being. Instead, it stabilizes the hindgut environment, allowing beneficial bacteria to flourish and removing potentially pathogenic bacteria. This is a common ingredient in many gut-related supplements but likely requires about 50 billion CFUs to have a positive impact, and few products provide these levels.
Hydrolyzed Saccharomyces cerevisiae yeast is another common ingredient that acts as a prebiotic, providing substrate for beneficial bacteria. I’ve also found it useful for horses with chronic loose stool.
Saccharomyces boulardii is a different strain of yeast shown in research to aid horses suffering from diarrhea and is considered a probiotic. This yeast helps inactivate or inhibit bacterial toxins through the release of a protease enzyme. Saccharomyces boulardii might also help horses with acute enterocolitis. Toxins produced by Clostridium difficile are major contributors to diarrhea in horses, and Saccharomyces boulardii has been shown to bind these toxins and remove them from the digestive tract.
Another toxin binder that might help horses with loose stool is smectite clay. Several forms of smectite clay exist, including sodium aluminosilicate and zeolite. These compounds have molecular structures and ionic charges that attract pathogenic bacteria and their toxins and smuggle them into voids from which they cannot escape. They are expelled from the digestive tract before they can cause harm. Smectite clays also bind mycotoxins, which are molds and fungi that exist in feed and can result in digestive disturbance such as diarrhea. Research exists showing that smectite clays can reduce the incidences of post-colic surgery diarrhea in horses. Hydrolyzed yeasts have also been shown to help reduce mycotoxins, and this might be another way in which they help reduce loose manure.
My other go-to product for horses with chronic diarrhea and loose manure is a hindgut buffer. This will help neutralize the hindgut pH to a favorable level for beneficial bacteria. I use this if I feel the issue might be the result of hindgut acidosis. In my experience using a hindgut buffer in combination with one of the above products can be very effective. Typically, you only need to provide the hindgut buffer for a short period until the hindgut environment stabilizes. The use of the pre- and probiotics might need to be longer term, depending on the horse. It might be possible to reduce their use and only provide them during periods of stress. However, I would recommend continuous use for horses in stressful environments or whose diets change frequently.
In my experience the solution for loose manure can vary by horse, so I commonly have to try a few different options before we find something that works. Which of these products I try first is typically driven by information provided to me by the client. If we try a product and find it ineffective, that provides further information about the underlying cause.