Equine Colic Beyond the Abdomen: The Emerging Role of the Gut Microbiome

Equine colic remains the most common emergency encountered in equine veterinary practice and one of the leading causes of mortality in horses worldwide. Traditionally, colic has been approached primarily as a gastrointestinal or mechanical disorder involving obstruction, displacement, gas accumulation, or strangulation of the intestines¹. However, growing evidence suggests that the gut microbiome may play a far more important role in colic pathophysiology than previously recognized. 

The Equine Gut Microbiome: A “Forgotten Organ” 

As hindgut fermenters, horses rely heavily on a stable and diverse intestinal microbial ecosystem for digestion, immune regulation, and maintenance of intestinal integrity². The equine hindgut contains billions of microorganisms including bacteria, fungi, protozoa, archaea, and viruses that collectively function almost like a separate metabolic organ³. 

These microbes are essential for¹: 

• Fiber fermentation  

• Production of short-chain fatty acids (SCFAs)  

• Maintenance of mucosal integrity  

• Immune modulation  

• Prevention of pathogen overgrowth  

Dysbiosis and Its Link to Colic 

When this microbial balance is disrupted — a condition termed dysbiosis — gastrointestinal dysfunction may follow⁴. 

Recent studies in horses with colic have identified: 

• Reduced microbial diversity  

• Increased lactic acid–producing bacteria  

• Expansion of streptococcal populations  

• Lower hindgut pH  

• Reduced abundance of beneficial microbes such as Akkermansia muciniphila⁵  

These changes may impair fermentation, alter intestinal motility, increase gas accumulation, and promote inflammation within the gut wall. 

Medical vs Surgical Colic: Why the Difference Matters 

Importantly, microbiome disruption appears particularly relevant in medical colic rather than surgical colic. 

Medical Colic 

Medical colic includes conditions such as: 

• Gas colic  

• Hindgut acidosis  

• Spasmodic colic  

• Functional ileus  

• Inflammatory intestinal disorders  

In these cases, dysbiosis itself may contribute directly to disease progression^2,6. 

Surgical Colic 

By contrast, surgical colic results from mechanical lesions such as: 

• Volvulus  

• Entrapment  

• Strangulating lipomas  

• Obstructions^1,7  

Although microbiome disruption may worsen inflammation in surgical cases, it is usually not the initiating cause. 

This distinction is clinically important because microbiome-targeted therapies may eventually become valuable preventive or adjunctive tools in medical colic management. 

The Growing Interest in Akkermansia muciniphila 

Among emerging microbial targets, Akkermansia muciniphila has generated significant attention. This mucin-degrading bacterium is increasingly recognized for its role in maintaining epithelial barrier integrity, regulating immune responses, and supporting metabolic homeostasis¹. 

In human and rodent studies, reduced abundance of A. muciniphila has been associated with¹: 

• Obesity  

• Diabetes  

• Inflammatory bowel disease  

• Metabolic syndrome  

Equine-specific research remains limited, but preliminary evidence suggests horses with colic may also exhibit reduced levels of this bacterium. 

Researchers caution, however, that this likely reflects broader dysbiosis rather than a single causative mechanism. 

What This Means for Equine Practice 

The future of equine colic research may increasingly focus on understanding how microbial ecology influences gastrointestinal resilience. While current evidence remains largely associative, it opens exciting possibilities for preventive strategies centered on nutrition, microbiome stability, and gut barrier protection. 

References  

1. Cottone A, Seiter K, Thomas B, Schank N, Wulf M, Miller L, Anderson S, Munkhsaikhan U, Verma A, Abidi AH and Kassan M (2026) The importance of prebiotics in managing colic in horses: focus on Akkermansia muciniphila and its anti-inflammatory potential. Front. Vet. Sci. 13:1759381. https://doi.org/10.3389/fvets.2026.1759381  

2. Chaucheyras-Durand F, Sacy A, Karges K, Apper E. Gastro-intestinal microbiota in equines and its role in health and disease: the black box opens. Microorganisms. (2022) 10:2517. https://doi.org/10.3390/microorganisms10122517  

3. Abeltino A, Hatem D, Serantoni C, Riente A, de Giulio MM, de Spirito M, et al. Unraveling the gut microbiota: implications for precision nutrition and personalized medicine. Nutrients. (2024) 16:3806. https://doi.org/10.3390/nu16223806  

4. Boucher L, Leduc L, Leclère M, Costa MC. Current understanding of equine gut dysbiosis and microbiota manipulation techniques: comparison with current knowledge in other species. Animals. (2024) 14:758. https://www.mdpi.com/2076-2615/14/5/758  

5. Park T, Cheong H, Yoon J, Kim A, Yun Y, Unno T. Comparison of the Fecal microbiota of horses with intestinal disease and their healthy counterparts. Vet Sci. (2021) 8:113. https://doi.org/10.3390/vetsci8060113  

6. Lara F, Castro R, Thomson P. Changes in the gut microbiome and colic in horses: are they causes or consequences? Open Vet J. (2022) 12:242–9. http://dx.doi.org/10.5455/OVJ.2022.v12.i2.12  

7. Vinijkumthorn R, Bauck AG, Vidyasagar S, Freeman DE. Nonsteroidal antiinflammatory drugs reduce anion secretion and increase apoptosis in equine colonic mucosa ex vivo. Am J Vet Res. (2023) 85:ajvr.23.08.0182. https://doi.org/10.2460/ajvr.23.08.0182