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March 31, 2023 — Probiotic awareness and use (whether through food or supplements) is becoming more common in horses and other equids. However, sorting fact from fiction can be tough. Supplementation can be expensive and horse owners are bombarded with advertisements and promotions encouraging the use of probiotics. Understanding more about what probiotics are and their potential actions can help horse owners decide if a probiotic is right for their horse.

Horses and Other Equids Have Complex Intestinal Tracts That Can Impact Probiotic Use

Horses and their close relatives, including ponies, donkeys and zebras, have digestive tracts that differ in significant ways from not only small animals, but also from other grazing animals such as cattle and deer.

Horses' stomach and small intestine are similar to humans, dogs and cats, but the business end of their digestive tract is, well, at the other end.

Horses digest fiber in their large intestine, which is huge compared to other companion animals, and comes toward the end of the digestive journey. Resident bacteria in the large intestine ferment fiber and release nutrients that are important sources of energy for horses. How these bacteria, and the balance of different bacteria in the large intestine, may impact disease and health, is the subject of ongoing research.

In theory, manipulating the bacteria in the large intestine might promote health and treat disease. The trick is getting the right bacteria to the right place - and then finding proof they actually help with a condition. This is much harder than it sounds.

What Is a Probiotic Anyway?

Most people have a general idea of what a probiotic is - maybe a cup of yogurt jumped to mind. But probiotics are much more complex and the science of creating them has advanced a lot in the last few years.

A probiotic is simply a collection of microorganisms packaged for oral consumption. Probiotics have been around a long time but the market for these compounds has exploded in the last 10-20 years.

The challenge with concocting the correct mix of organisms to restore health is that we still don't have a good idea of what constitutes normal. Adding to the difficulty is figuring out how to get the organisms to the correct portion of the gut where they can be most beneficial for the patient. Given what we know about horse anatomy, this means trying to deliver a product quite a way down the intestinal tract.

Conversely, we know that the gut microbiome can influence health in ways that extend way beyond simply assisting in food digestion. For this reason, there is a lot of research in both academic and corporations focused on finding better ways to alter gut microbial populations.

Many probiotics are already in use in horses and, while hard scientific data is lacking when it comes to efficacy, the vast majority of veterinarians and other equine health specialists agree that probiotics are safe for most horses.

Manipulating the Gut Microbiome for Better Health – The Final Frontier?

For many researchers, the ability to precisely alter the gut microbiome to improve health or as part of the treatment for a specific disease could be a new and powerful method to treat intractable health problems.

Some researchers continue to work on new oral probiotic cocktails as a way of altering gut microorganisms, and still others are looking at how diet alterations might change the microbiome.

Morris Animal Foundation has funded several research projects that have increased our knowledge of how this complex population affects the health of horses. One project noted how the bacteria change in conditions similar to starch-induced laminitis and identified bacteria that could be beneficial as probiotics. Another funded study was one of the first studies describing the bacteria found in foals, and how it changes over time.

Ongoing studies include a further look at how the microbiome influences starch metabolism in the hope of identifying bacterial factors that contribute to serious and often fatal diseases such as diarrhea, colic and laminitis.

Manipulating gut bacteria to maintain good health and prevent disease through the use of probiotics represents the cutting edge of medical research. Morris Animal Foundation has a long history of funding innovative research to improve the lives of all animals worldwide. Learn more about how the Foundation is investing in probiotic and microbiome research, as well as our other equine studies. Together, we can make the future brighter for horses and all animals everywhere.


Learn more about equine nutrition in general: