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Microbes and Equine Gastrointestinal HealthBy Kentucky Equine Research Staff · November 29, 2016

A complex microscopic world thrives inside the gastrointestinal tracts of healthy horses. Pinpointing surefire ways to optimize and stabilize these microscopic organisms will benefit horses immensely, especially in times of stress or illness.

Probiotics are live-fed microorganisms, usually in paste or powder form, given to achieve digestive normalcy in both humans and horses. The claimed benefits associated with probiotic administration are vast and varied. For example, probiotics are reported to:

  • Facilitate immunomodulation by keeping the host immune system primed to respond more quickly and effectively to infection;
  • Improve gut health in patients with inflammatory bowel diseases;
  • Help prevent antibiotic-induced diarrhea; and
  • Protect against infectious agents that cause diarrhea, such as Salmonella spp.

To date, thousands of microorganisms have been identified in the equine intestinal microbiome. Which of those species confer the greatest benefit as a probiotic, how much should be administered, and how often a horse should be offered a probiotic supplement remain unclear. To date, various probiotic organisms have been suggested based on the analysis of “normal” feces from healthy horses, including lactic acid bacteria (LAB).

Unfortunately, despite the widespread acceptance that probiotics are beneficial, not all studies show that microbes have probiotic potential. Further, not all studies reveal that feeding bacteria to animals is safe. One recent article* reported that a presumptive probiotic LAB organism obtained from healthy foal feces actually made things worse.

In that study, mice were supplemented with Pediococcus pentosaceus strain #40 before and after challenging the mice with Salmonella. Instead of protecting the mice against infection, supplemented animals had increased weight loss, worsening of clinical signs of disease, and more deaths than unsupplemented animals.

Considering the exquisitely sensitive nature of the equine gastrointestinal tract, an effective probiotic for horses is desirable yet elusive, said Catherine Whitehouse, M.S., a nutrition advisor for Kentucky Equine Research (KER).

“In the meantime, support gastrointestinal health through appropriate nutrition. In addition, consider supporting your horse’s dietary health in times of stress or dietary change with EquiShure, a time-released buffer that helps control the pH level and stabilize the microbiome in the hindgut,” said Whitehouse.

Consult with a KER nutritionist today for more information.

*Silva, B.C., S.H. Sandes, L.B. Alvim, et al. Selection of a candidate probiotic strain of Pediococcus pentosaceus from the faecal microbiota of horses by in vitro testing and health claims in a mouse model of Salmonella infection. Journal of Applied Microbiology. In press.