Large colon resection.

This study finds that large colon resection, a surgical procedure in which a significant portion of a horse’s large colon is removed, while successful, can lead to permanent deficits in the animal’s nutrient absorption. These deficits, however, can be managed by adjusting the horse’s diet, specifically feeding it alfalfa hay and allowing it unrestricted access to water.

Objective of the Research

• The objective of this research was to investigate the effects, both immediate and long-term, of large colon resection on horses and to identify dietary adjustments that can mitigate the impacts of this surgery. The surgery involves removing up to 95% of the large colon’s length, addressing issues found in the left dorsal colon and pelvic flexure.

Methodology

• The authors detail two methods of performing the large colon resection, namely the hand-sewn end-to-end anastomosis for lesions in the left dorsal colon and pelvic flexure and the transection and side-to-side anastomosis with stapling equipment for more extensive resections (more than 50% of the colon).

Findings

• The research found that even successful large colon resections result in permanent deficiencies in the horse’s ability to absorb water and digest cellulose and protein. The horse’s capacity for fermentation is also affected due to a shortened retention time of particulate matter in the smaller capacity colon post-surgery.
• The study suggests that these deficits can be mitigated to an extent by feeding the horse alfalfa hay (at about 2% of the horse’s body weight). This adjustment makes it possible to maintain normal blood variables and keep the horse’s body weight up.
• The horses also exhibited increased voluntary intake, which presumably helps maintain a positive nutrient balance post-surgery. Grass hay was found to be insufficient as the sole source of energy and protein due to its higher cell wall content. Such a diet would result in weight loss in the horse.
• Because the surgery results in increased fecal water loss, the study recommends that horses have ad libitum (at will) access to water at all times.