There are always risk factors when horses undergo surgery and anesthesia. Researchers have found that these risks are greater in horses than any other animal species. Studies have also shown that colic surgery mortality rates are higher than that of any other surgical procedure–most likely because the horse’s system is already compromised when the animal is anesthetized.

To better understand this, researchers at the University of Liverpool in Neston, Wirral, United Kingdom, identified risk factors associated with mortality rates in emergency colic surgeries.

Chris Proudman, MA, VetMB, PhD, CertEO, FRCVS, a professor of equine studies at the university, and his fellow researchers recorded data for 637 horses that underwent colic surgery. They identified significant risk factors that affected the horses’ survival rates such as PCV (packed cell volume), and heart rate–which are measurements of endotoxemia (endotoxins from the intestines are released into the bloodstream)–age, breed, and level of pain. Of the 637 study horses, 88 (approximately 14%) died or were euthanatized during surgery.

Heart rate, PCV, age, and breed type were directly related to the study horses’ mortality rate. "Age was significantly associated with the post-op death; there was a small increase in risk for each year of age," Proudman explained