Intestinal bacterial overgrowth includes potential pathogens in the carbohydrate overload models of equine acute laminitis.

The research article examines how a shift in the bacterial communities in a horse’s digestive system, caused by a high-carbohydrate diet, can contribute to the development of acute laminitis, a condition which causes lameness in horses.

Overview of the Study

• The study builds on the premise of “carbohydrate overload” models of equine acute laminitis, a painful condition affecting horse’s feet.
• The research investigates the hypothesis that a diet high in carbohydrates can cause a shift in the bacterial communities in the cecum (part of a horse’s gut), leading to an overgrowth of potentially harmful bacteria.
• This overgrowth is proposed to contribute towards a pro-inflammatory state, which then progresses to a laminitis condition marked by severe inflammation and failure of the laminae (sensitive tissues within the horse’s hoof).

Methodology and Findings

• Two groups of mixed-breed horses were used in the study, one group with laminitis induced by cornstarch, another by oligofructan, and a control group of non-laminitis horses.
• The cecal fluid and tissue homogenates of extra-intestinal sites including the laminae were used to count the amount of Gram-negative and Gram-positive bacteria.
• The study found a significant increase in potentially harmful Gram-positive and Gram-negative bacteria within the cecal fluid of horses that developed an Obel grade2 lameness, a measure of the severity of laminitis.
• While the research did not detect the colonization of extra-intestinal sites with these potentially harmful bacteria, it noted the development of lymphadenopathy (disease of the lymph nodes) and eosinophilia (increase in eosinophils, a type of disease-fighting white blood cells) in the horses progressing to lameness.

Conclusion and Recommendations

• The research concludes that the pro-inflammatory state observed in carbohydrate overload models of equine acute laminitis is possibly driven by an immune response to an abrupt overgrowth of harmful bacteria in the cecum of horses.
• The study suggests that further research in equine health should focus on studying the immunological response, especially within the lymphatic system that develops as a result of the carbohydrate overload-induced bacterial overgrowth in the model.