Use of Intraperitoneal Lidocaine in Horses Undergoing Laparotomy for Colic.

Administering lidocaine into the abdominal cavity at the end of colic surgery did not significantly improve early postoperative pain outcomes in a prospective, randomized clinical trial involving 54 horses. The study, by Federica Giulivi and Sara Nannarone at the University of Perugia, was published in Animals on May 26, 2026.

Why investigate this approach?

Lidocaine is used perioperatively in horses with acute abdominal disease for its potential analgesic, prokinetic, anti-inflammatory and anti-endotoxic effects. However, evidence for its effectiveness against visceral pain remains inconclusive. The researchers investigated whether intraperitoneal administration could improve recovery from anesthesia and pain during the first 24 hours after laparotomy for colic.

How the trial was conducted

The unblinded trial allocated horses equally between two groups. Twenty-seven horses received intraperitoneal lidocaine at 2 mg/kg at the end of laparotomy; the other 27 did not receive intraperitoneal lidocaine. Pain was assessed using a Multifactorial Numerical Rating Composite Pain Scale for equines.

The analysis also considered the cause of colic, duration of surgery and anesthesia, recovery time, American Society of Anesthesiologists (ASA) physical status, and whether horses received a postoperative constant-rate infusion of lidocaine.

What the researchers found

The intraperitoneal lidocaine group showed a trend toward faster pain reduction, but the difference in early postoperative pain outcomes was not statistically significant. No horse showed signs of toxicity during the study.

Higher pain scores were associated with postoperative lidocaine infusion, higher ASA status, longer recovery time and large intestinal disease compared with small intestinal disease. Postoperative lidocaine infusions were associated with more severe cases, so that association should not be interpreted as proof that the infusion caused greater pain.

Clinical interpretation

These results do not establish a clear early analgesic benefit for this intraperitoneal protocol. The absence of observed toxicity in a small trial also does not establish safety for every patient or dosing regimen. The unblinded design and the influence of disease severity are important considerations when interpreting the findings. Further research is needed to define effective protocols and identify which horses, if any, may benefit.

This is an editorial summary of the published research, not an individual treatment recommendation.

Source

Giulivi F, Nannarone S. Use of Intraperitoneal Lidocaine in Horses Undergoing Laparotomy for Colic. Animals. 2026;16(11):1616. Read the original open-access study.