Probiotics In Horse Diets

Are probiotics good for horse health? Probiotics are defined as live microorganisms that, when administered in adequate amounts, confer health benefits on the host. They function by enhancing the gut microbiome—the community of beneficial bacteria in the digestive tract—which improves digestion and boosts the animal’s immune system.

Helpful microorganisms in the GI tract aid in breaking down feed, allowing for better absorption of nutrients. They can even protect against pathogens by outcompeting them for resources within the gut.

Supplementing your horse with probiotics could potentially help that animal maintain a balanced intestinal environment. This is especially beneficial during times of stress, such as during transport, illness, exercise, or changes in diet. A balanced gut microbiota is linked with improved overall health, potentially leading to better performance and a more resilient digestive system.

(Editor’s note: Both prebiotics and probiotics are areas that need further research in the horse. Much of the information on prebiotics and probiotics in the diet has been done in other species and extrapolated to the horse. It can be advisable to talk to your veterinarian or an equine nutritionist before using either of these as any changes you make in your horse’s diet can have unwanted consequences.)

Probiotics for Horses

There are many ways that probiotics are used in human and animal health. But since each horse’s situation (and therefore their GI tract microbiomes) are different, there is no “one product fits all” situations.

A study conducted on Thoroughbreds found that certain strains of lactobacilli and bifidobacteria exhibited anti-inflammatory and intestinal barrier-protective activities.¹ Other research revealed that probiotic supplementation could influence the microbial diversity in the GI tract microbiome of healthy horses.²

Donkeys are more efficient animals designed to graze on coarse vegetation with limited water. They are genetically designed to have a lower metabolic function (and lower energy requirements).³ Researchers have found that donkeys have a gut microbiome mix of microbes that is better at extracting energy from fiber than that found in horses.⁴

Potential Risks and Side Effects

While probiotics are generally considered safe for equine use, it’s crucial to understand the potential risks and the importance of proper regulation. Despite the potential benefits probiotics offer, there is a recognized need for cautious application when it comes to equine health.

Not all probiotic strains are equal in their efficacy or safety, and the inappropriate use of probiotics can lead to unforeseen complications. Some animals might experience side effects such as bloating, gas, or discomfort, particularly when introduced to a new probiotic regimen. Others might have more serious issues, such as severe diarrhea or laminitis.

Horse owners should also consider that most manufacturers of probiotics are unregulated. That means products could contain impurities or incorrect strains of organisms that could negatively impact the animal’s health instead of providing the intended benefits. They could also be completely lacking in live microorganisms.

There might be added risks with immunocompromised horses, donkeys, and mules, as well. Introducing live bacteria into their systems might inadvertently cause GI tract imbalances and issues.

Even in healthy animals, an imbalance caused by an overabundance of certain probiotic microorganisms can disrupt the gut microbiome, potentially leading to a state called dysbiosis. This is an imbalance in bacterial composition, changes in bacterial metabolic activities, or changes in bacterial distribution within the gut.

While these events are uncommon, they underscore the importance of veterinary or nutritionist guidance when incorporating probiotics into an animal’s diet. Careful selection of strains, appropriate dosages, and constant health monitoring are key to safely leveraging the positive effects of probiotics while minimizing potential downsides.

Final Words

It can be advisable to consult with an experienced veterinarian or equine nutritionist before introducing any new supplements into your horse’s diet. Nettie Liburt, PhD, PAS, summarized prebiotics and probiotics this way:⁵

Microorganisms in the equine digestive tract play an important role in maintaining overall health.
Changes in the microbiome affect equine health, and vice versa.
Our understanding of the proper use and efficacy of probiotics in horses is limited, and much remains to be learned.
Probiotics are not recommended for neonates, but they might be part of a supportive nutrition program for horses receiving antimicrobials.
Yeast appears to help improve fiber digestion.
Prebiotics are food for the microbiome and help support a healthy microbial population in the digestive tract.
Prebiotics might help support the immune system, especially in aging horses.