Cribbing: More Evidence for Microbiota-Gut-Brain Axis in Horses

Although cribbing affects approximately 13% of all horses, the cause of the behavior remains unclear. In a recent study, horses that cribbed had significantly different microbial communities compared to those not displaying the stereotypy, suggesting the microbiota-gut-brain axis may be involved.^*

In the study, fecal samples were collected from six horses that cribbed and six that did not. Horses were all managed similarly and otherwise healthy. Based on standard fecal microbiome analysis (evaluating the 16S ribosomal RNA gene amplicons), the fecal bacterial community structures were evaluated.

“In both populations, the standard bacterial phyla were identified, including Firmicutes, Bacteroidota, and Spirochaeota. At the family level, Lachnospiraceae, Ruminococcaceae, and Prevotellacea were all present, as expected, in all horses,” said Ashley Fowler, Ph.D., a Kentucky Equine Research nutritionist.

However, the cribbing horses had a greater relative abundance of Ruminococcaceae, and the control horses had a significantly greater abundance of Lachnospiraceae.

These findings suggest “the possibility that the microbial composition of the intestine plays a role in the etiology of this oral stereotypy,” wrote the researchers. The proposed mechanism is through a microbiota-gut-brain axis.

Further analysis of the fecal samples was performed to evaluate “functional profile.” In the control horses, multiple metabolic pathways were overrepresented, including those involved in biotin and vitamin B6 synthesis. In the cribbing horses, many pathways were also overrepresented, including polysaccharide degradation and the biosynthesis of various amino acids.

“These results suggest that the two groups of horses have differences in both the composition and function of the intestinal microbiota,” Fowler said. “This study doesn’t, however, indicate if the change in the microbiome causes cribbing or if cribbing causes the change in the microbiome.”

While more is being unearthed on this topic, offering supplements to stabilize the hindgut such as a hindgut buffer may be beneficial.

“EquiShure is a time-released buffer that works in the hindgut of the horse to stabilize the intestinal pH. Ensuring a consistent pH can help encourage a stable microbiome,” explained Fowler.

^*Martínez-Aranzales, J.R., M. Córdoba-Agudelo, and J.E. Pérez-Jaramillo. 2024. Fecal microbiome and functional prediction profiles of horses with and without crib-biting behavior: A comparative study. Journal of Equine Veterinary Science:105198.