The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.
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30 TheHorse.com THE HORSE December 2017 rapidly making new discoveries about how it reacts to many variables. Here is a recap of some of that research. Microbial Stability Researchers knew horses' gut microbiota can change rapidly with dietary concentrate or forage adjust- ments, potentially leading to GI upset. But it wasn't clear whether gut micro- biota change or remain stable in pastured horses receiving supplemental forage and no concentrate feed. So, researchers from the Universities of Liverpool and Leicester, both in the U.K., conducted a yearlong study to find out. They found that pasture-kept horses' microbial popu- lations are in a slow, but constant, state of change in response to factors such as season, weather, and the type of forage they're eating. The same research team also evaluated gut microbiota in periparturient (around the time of foaling) broodmares, a group of horses known to be at risk for colic. "Alterations in colonic microbiota related to either physiological or manage- ment changes, or both, that occur at this time have been suggested as potential causes for increased colic risk in this population," said Shebl Salem, MS, PhD, a research assistant at the University of Liverpool. Salem collected and evaluated fecal samples from broodmares for five weeks before and 12 weeks after foaling. None of the mares colicked, and their fecal mi- crobiota was fairly consistent. He did find microbial population variations between horses. "If differences in gut microbiota are associated with colic in broodmares postpartum, altered risk may be due to inherent differences between individual mares rather than being related to man- agement changes that occur during this time," he said. Medication's Effects Researchers have been studying how medications affect the gut's good microbial population. In one recent study veterinarians and scien- tists at Texas A&M; University collected fecal and cecal samples to evaluate the microbiota and metabolome (similar to a microbiota, but made up of metabo- lites) before and after administering the antimicrobial metronidazole to five adult horses. They found that metronidazole impacted both the microbiome and the metabolome significantly, reducing the population diversity in the treatment group. In another study Colorado State Uni- versity (CSU) researchers tested whether one prebiotic and probiotic supplement could affect the metabolome following 14 days of antibiotic administration. Researcher Diana Hassel, DVM, PhD, Dipl. ACVS, ACVECC, an associate pro- fessor of equine emergency surgery and critical care at CSU, said analysis of their data revealed "some distinct separations between fecal metabolic features between treatment groups at Day 14, suggesting that probiotic administration has a sig- nificant impact on fecal metabolites, and these metabolites more closely resemble those of control samples compared with antibiotic treatment alone." The bottom line: Antibiotics do alter the fecal metabolome, and probiotic administration along with antibiotics might help normalize it. Researchers from the University of Leipzig, in Germany, compared the intestinal microbiota of healthy horses, horses with acute colitis, and diseased horses without intestinal disorders, counting numbers of three types of bacteria— Eubacteria, Bifidobacteria, and Cytophagia. The latter two groups received treatment during the study: Colitis horses received fluids, amoxicillin every 12 hours, and gentamicin every 24 hours, while the other diseased horses received the same antibiotics over seven days. Healthy horses had free-choice ac- cess to hay. "The Eubacteria and Bifidobacteria in fecal samples were significantly reduced in horses with acute colitis in comparison with normal horses at admission," said researcher Prof. Gerald Fritz Schusser, Dr., Dipl. ECEIM, "Further studies are needed to analyze the numbers of normal bacteria in horses with acute colitis treated with equine fecal microbiota transplantation." This procedure involves administering feces from healthy horses by enema or nasogastric tube to diseased horses and has been theorized to help re- build sick horses' microbial populations. Another research team, this one from the University of Georgia, looked at the effects of the proton pump inhibitor omeprazole—used to treat and prevent gastric ulcers—on horses' gut microbiota. They tested omeprazole for two reasons: ■ In humans proton pump inhibitors have been associated with infectious gastrointestinal problems and a change in gastrointestinal microflora; and ■ Veterinarians and researchers have observed that foals treated with proton pump inhibitors have a higher inci- dence of diarrhea than untreated foals. However, they found that the treatment and placebo groups' fecal microbiota composition and diversity did not differ significantly over time. Omeprazole administration doesn't have a marked effect on healthy horses' fecal microbial diversity, they concluded. Scientists also examined the anthel- mintic drug (dewormer) moxidectin's effects on the gut microbiota. A research team from the Royal Agricultural Univer- sity, University of Surrey, and Imperial College, all in the U.K., had three goals— to determine whether moxidectin: ■ Altered the gut microbiota composition; ■ Was metabolized by the bacteria; and COLIC: An Ever-Evolving Issue German researchers compared the intesti- nal microbiota of healthy horses (top) with that of horses with acute colitis (above). COURTESY DR. GERALD FRITZ SCHUSSER Symposium TWEET Erica Larson @TH_EricaLarson Barton says she sees more chronic gastric impactions in Friesians compared to other breeds. Vets in attendance agree.