FMT: Providing Intestinal Health and Hope for Older Horses

If you’re lucky enough to keep your horse well into its retirement years, or have a sound senior horse that you still ride, maintaining good gut health is vital. Colic is a looming threat for any horse owner, but for horses of a certain age gut inflammation that results in colitis and diarrhea is also an issue that can result in hospitalization and in severe cases, require euthanization.

A new study from Tufts University’s Cummings School of Veterinary Medicine in Massachusetts was able to prove that pumping a watery “soup” of fresh feces into the affected horse’s stomachs by nasogastric tube could alter the composition of the microorganisms in the intestines and thus improve the condition to the point of the animal being a healthy discharge from the hospital.

The study’s initial goal was to use this method of fecal microbial transplantation (FMT), as a treatment for horses hospitalized with colitis to evaluate whether the procedure restored microbiota diversity. The treatment is also used in humans to treat gastrointestinal conditions associated with dysbiosis. The researchers used what is called microbiota high-throughput sequencing to compare the fecal microbial profile of healthy horses to that of geriatric microbial transplant recipients experiencing diarrhea and tested whether FMT restores microbiota diversity.

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To test their theory, the scientists performed genomic sequencing on the horse’s microbiomes as well as on 30 healthy horses (15 young horses, 15 seniors), which included three horses randomly selected as donors. FMT was given as a treatment for three consecutive days in the five senior equine patients using feces from the same healthy donor. Fecal samples were collected from both donor and recipient prior to each FMT and from recipients 24 hours following the last FMT.

According to the published report, the researchers noted two trends distinguishing healthy horses from those with colitis: the number of different kinds of bacterial species and the total number of Verrucomicrobia (a bacteria that contributes to intestinal health) were both lower in horses with diarrhea in this population.

Another interesting finding was that “age did not significantly affect the healthy equine fecal microbiota, indicating that both healthy geriatric and young-adult horses may serve as FMT donors.”

The results of the FMT were that three of the five senior patients recovered from the diarrhea and had improvements in their microbiomes following the fecal transplants. Sadly, the other two horses did not recover and had to be put down. However, in both of those cases there were issues that were outside the scope of FMT; one had a large intestinal stone that caused the diarrhea while the other horse had pneumonia and was placed on antibiotics, a factor that, according to the scientists, may have affected the guts’ ability to repopulate bacteria.

“The procedure of fecal transplant itself isn’t novel, and in fact it dates back to at least 4th-century China, when it was used in humans,” Dr. Daniela Bedenice told one publication. “We’ve been treating horses with fecal transplants in our clinic for several years now, with good results. But this is the first time, thanks to genetic sequencing, that we’ve been able to see what’s actually happening in the microbiome when these transplants occur.”

The vets who worked on the study want to strongly caution owners not to try this at home by mixing a healthy horse’s manure into the feed/water of a sick horse. Instead, the ill animal needs to have testing performed by a veterinarian to rule out parasites and the like and if FMT is used, it should only be performed at an equine vet clinic.