How Diet Affects Equine Gut Health

What we’re learning about this dynamic area of research and how we can use it to promote equine health 

Blue colicked in his stall so violently, the farm’s vet in Baltimore, Maryland, immediately arranged transport to a referral hospital. The 10-year-old off-track Thoroughbred went down in the trailer several times before arriving at New Bolton Center, in Kennett Square, Pennsylvania. There, he underwent successful surgery for large colon volvulus.

“We thought he’d be on his way back home within the week,” recalls his owner, Karin de Francis. “But then, the odyssey started.”

Blue colicked again several days after surgery but responded to pain medications. A week later he colicked again. Then again, and again. Despite diet changes, anti-ulcer medications, and pain management, Blue continued to show intermittent signs of mild colic. His veterinarians couldn’t find anything on ultrasound or X ray. Even his intestinal biopsies were normal, leaving his caretakers frustrated about how to help.

“He kept having these repeat, medicaltype colics that didn’t need surgery,” says Alicia Long, DVM, emergency and critical care fellow at New Bolton. “And when we did some digging into his history—back to his life on the track—we learned that he was known for being ‘ulcery.’ ” Blue never got scoped for ulcers, though, and his bouts of lying down and not wanting to eat might have been from colic instead.

At New Bolton, Blue journeyed in and out of colic episodes for the next 10 months, finally going home healthy in July 2021. As the gray gelding’s gut oscillated between stable and chaotic, on the outside scientists worldwide were delving into the guts of humans and horses alike, using the latest genetic sequencing technology to better understand the vast and mysterious world of the microbiome. With more than 8,000 peer-reviewed papers published on the gut microbiome while Blue was hospitalized, including dozens specifically on horses, the scientific world was exploding with new information about these microscopic communities inhabiting the digestive tract.

In a way, Blue’s timing was perfect. His case inspired the New Bolton team to explore the possible links between the gut microbiome, diet, and recurrent colic.

What’s particularly exciting, Long says, is it could lead to a hands-on fix for owners. “Diet is something we can do, something we can change,” she says. “If you can change dietary management, then theoretically you could potentially help reduce risk of colic—and that’s really the white whale in equine research right now.”

The New Bolton team, including Blue’s surgeon, Louise Southwood, BSc (Vet), Dipl. ACVS, ACVECC, has joined the international push to unveil the microbiome’s secrets, with potentially revolutionary ways to manage horses’ digestive health. In this article we’ll review what scientists are

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