Functional morphology of the equine pelvic flexure and its role in disease. A review.

The research paper discusses the role of the pelvic flexure in a horse’s digestive system, particularly its involvement in the regulation of aboral and retropropulsive transit of digested food, and its correlation to the pathophysiology of colic, a common cause of death in horses.

The Equestrian Digestive System

• This study explores the complexity of the horse’s digestive system, especially focusing on the large intestine compartments (cecum, right and left ventral colon, left and right dorsal colon).
• The hindgut, a crucial component of the digestive system, is the major site for nutrient absorption and digestion in horses.

Role of the Pelvic Flexure

• The pelvic flexure is a short and narrow loop establishing the connection between the left ventral and left dorsal colon.
• Although the pelvic flexure is not directly linked to digestive and absorptive processes, it plays a significant role in regulating the passage of digesta from the colon in both forward and reverse motion through its motility pacemaker activity.

Contribution to Colic Pathophysiology

• The study highlights the correlations between the pelvic flexure and colic in horses. Colic is the leading cause of death in horses and is strongly related to the functional aspects of the pelvic flexure.
• The narrow lumen of the pelvic flexure can contribute to colonic impaction. Moreover, malfunctions of the pacemaker might lead to volvuli (twisting of the intestine) and colonic displacements.

Morphological and Neuroendocrine Observations

• The research reveals an increased neuronal and ganglion density at the pelvic flexure and its adjacent left dorsal colon pacemaker region.
• The activity of contractile elements, vasoactive intestinal peptides (VIP), and neurokinins-1 and -3, is all enhanced in the pelvic flexure region.
• Upon microscopic examination, the mucosa of the pelvic flexure shows similarities to that of the ventral and dorsal colon, with distinct microscopic features observed in the main cells.

Conclusion and Further Research

• The researchers conclude that additional in-depth investigation into the pelvic flexure’s neuroendocrine and morphological features is warranted, given this particular region’s vital role in both normal function and pathophysiology in horses.