Feeding before surgery may improve recovery in horses

CURRENT FULL VERSION: A long-standing equine surgery routine is getting a second look: fasting horses before elective, non-abdominal surgery may not help, and it may actually worsen postoperative gut outcomes. Colorado State University clinicians studied horses undergoing elective orthopedic procedures and found that those allowed access to hay until roughly one hour before anesthesia had earlier and greater manure output after surgery, with no reported increase in anesthetic complications. Coverage of the study also noted postoperative colic in four of 30 fasted horses and none in the fed group. The work was later discussed on the AVMA’s Veterinary Vertex podcast as a “myth-buster” that directly challenged a protocol many hospitals had followed for years simply because it was standard practice. (paulickreport.com)

The finding matters because preoperative fasting has been common in equine practice for years, largely based on concerns about colon size, respiratory compromise under anesthesia, and postoperative colic risk. As described in the Veterinary Vertex interview with study author Charlie Barton, CSU had historically fasted horses for six to eight hours before general anesthesia across elective cases, and some horses were also muzzled when housed on straw bedding, underscoring how restrictive these protocols could be in practice. But horses are not small animals, and the physiologic rationale for fasting has always been somewhat uneasy. Unlike in dogs and cats, regurgitation under general anesthesia is rare in normal horses, and some researchers have argued that restricting forage may suppress gut motility and water intake, both of which could increase colic risk rather than reduce it. (pmc.ncbi.nlm.nih.gov)

This newer CSU work builds on an older evidence base that had already raised doubts. A 2016 retrospective study of non-fasted adult horses undergoing elective, non-abdominal procedures found a 2.5% incidence of post-anesthetic colic, lower than previously published reports in mostly fasted populations. The authors suggested free-choice access to food and water before anesthesia may help maintain normal intestinal activity. More recently, a 2024 retrospective cohort study reported that fasting, longer surgery duration, and increasing age were all significantly associated with post-anesthetic colic, with fasting carrying an odds ratio of 2.7. (pmc.ncbi.nlm.nih.gov)

The CSU study adds a prospective, practice-facing angle that clinicians can use more readily. According to summaries of the work, horses in the fed arm had hay available continuously until one hour before anesthesia and resumed hay 30 minutes after recovery, while fasted horses had hay removed about 10 hours before surgery and were gradually refed later. Reported outcomes favored feeding: faster return of fecal output, higher manure production postoperatively, and no apparent increase in anesthesia-related complications. Rachel Hector, a CSU clinical instructor in anesthesia, described feed restriction as a major stressor for hospitalized horses and said the work prompted CSU and other hospitals to rethink routine fasting practices. In the Veterinary Vertex discussion, Barton also emphasized that the project began as practical clinical research aimed at testing whether a protocol that had been in place “since forever” was actually helping patients. (ker.com)

Industry and expert commentary has been notably practical rather than flashy. Kentucky Equine Research highlighted postoperative colic as a complication seen in roughly 3% to 11% of anesthetic cases and emphasized that delayed manure passage can signal slower gastrointestinal recovery. IVIS conference material similarly notes that fasting decreases myoelectric activity in the equine colon, reducing contractile activity, while also cautioning that feeding before surgery may not be appropriate for every case, particularly laparoscopic procedures where gut fill and gas can interfere with access and visibility. The broader anesthesia context also matters: in a separate Veterinary Vertex episode on equine sedation and anesthesia, AVMA editors noted that large international data continue to put overall perioperative mortality for horses undergoing general anesthesia at about 1.2%, a reminder that even routine anesthetic management decisions deserve scrutiny when recovery quality and complications are on the line. (ker.com)

Why it matters: For veterinary teams, the takeaway isn’t that every horse should always be fed before every procedure. It’s that blanket fasting protocols for elective, non-abdominal surgery look increasingly hard to justify. If maintaining forage access improves welfare, preserves gut motility, and lowers the odds of post-anesthetic colic, that can affect anesthesia instructions, inpatient nursing protocols, postoperative monitoring, and discharge conversations with the pet parent. It may also reduce one of the more common and costly complications after equine anesthesia. And because horses remain a comparatively high-risk anesthesia species overall, small protocol changes that improve recovery without adding anesthetic complications can carry outsized practical value. Still, practices will need to balance these benefits against procedure type, surgeon preference, and individual patient factors such as age, case complexity, and anticipated anesthesia duration. (pmc.ncbi.nlm.nih.gov)

What to watch: The next step is likely protocol refinement, not wholesale reversal. Expect more referral centers to distinguish between elective non-abdominal cases, where feeding may become standard, and procedures such as laparoscopy, where some fasting may remain advisable. The evidence is moving toward less restrictive feeding in selected horses, but prospective controlled studies and hospital-level outcomes will determine how quickly that shift becomes mainstream. (pmc.ncbi.nlm.nih.gov)