Post-operative ileus after colic surgery in horses: intravenous lidocaine CRI vs standard care/placebo — POSSIBLE

In horses with post-operative ileus after colic surgery, does an intravenous lidocaine constant-rate infusion shorten the duration of ileus/reflux and hospitalisation compared with saline placebo or standard care?

Shelf #179 · gate-verified and displayed under the developer's blinded-trial rule

POSSIBLE: The one blinded, placebo-controlled trial is positive on reflux but not on survival, and the largest dataset is null — the evidence is genuinely split. In Malone 2006 (32 already-refluxing horses with post-operative ileus or enteritis, prospective double-blinded placebo-controlled), 65% (11/17) of lidocaine horses stopped refluxing within 30 hours versus 27% (4/15) on saline, and hospitalisation was shorter for survivors, with survival to discharge equivalent. In Brianceau 2002 (28 colic-surgery horses, randomly assigned), lidocaine improved jejunal ultrasound measures and peritoneal fluid findings but showed no significant difference in gastric reflux, time to first feces, complications or outcome. A retrospective study of 126 small-intestinal surgery horses associated prophylactic lidocaine with lower odds of ileus (OR 0.25) and enhanced short-term survival (Torfs 2009), but in 318 UK horses perioperative lidocaine had no effect on reflux prevalence, volume or duration, or on post-operative survival (Salem 2016). Gaps: no large multicentre randomised trial exists (Salem's authors call for one); treatment of established ileus (Malone) and perioperative prophylaxis (Brianceau, Torfs, Salem) are mixed across the cards, and the positive retrospective associations are open to confounding by indication and era. Drafted Nov 10, 2026 (VetMed build, topic #179); all figures from abstracts fetched and verified at drafting.

Malone 2006: 65% of lidocaine horses stopped refluxing within 30 hours vs 27% on saline placebo, with shorter hospitalisation for survivors and equivalent survival

Prospective double-blinded placebo-controlled trial (record's own wording); publication types: Randomized Controlled Trial, Multicenter Study

Who: Horses: 32 horses with a diagnosis of postoperative ileus (POI) or enteritis and that had refluxed >20 L or had been refluxing for >24 hours, in a multicentre clinical setting. Refluxing horses were administered lidocaine (1.3 mg/kg intravenously as a bolus followed by a 0.05 mg/kg/min infusion) or saline (0.9% NaCl) solution placebo for 24 hours; variables evaluated included volume and duration of reflux, time to 1st fecal passage, signs of pain, analgesic use, heart rate and arrhythmias, respiratory rate, temperature, days of hospitalization, outcome (survival to discharge) and complications. The reported results cover 17 lidocaine-treated and 15 saline-treated horses.

Result: Of the lidocaine-treated horses, 65% (11/17) stopped refluxing within 30 hours (mean+/-SD, 15.2+/-2.4 hours) whereas 27% (4/15) of the saline-treated horses stopped within 30 hours. Fecal passage was significantly correlated with response to treatment; horses that responded to lidocaine passed feces within 16 hours of starting the infusion. Compared with placebo treatment, lidocaine treatment resulted in shorter hospitalization time for survivors, equivalent survival to discharge, no clinically significant changes in physical or laboratory variables, and no difference in the rate of incisional infections, jugular thrombosis, laminitis, or diarrhea. Muscle fasciculations occurred in 3 lidocaine-treated horses (18%).

Watch out: The population mixes post-operative ileus with enteritis, so this is a treatment trial in already-refluxing horses, not a pure post-colic-surgery prophylaxis trial. Hospitalisation was shorter only among survivors and survival itself was equivalent, so no survival benefit is shown. The record's design wording states double-blinding and its publication types include Randomized Controlled Trial, although the abstract does not describe the randomisation method.

Malone E, Ensink J, Turner T, Wilson J, Andrews F, Keegan K, Lumsden J. Intravenous continuous infusion of lidocaine for treatment of equine ileus. Veterinary surgery. 2006;35(1):60-6. PMID: 16409411. Registry ID: none in the record. MeSH: Abdominal Pain/epidemiology · Abdominal Pain/veterinary · Anesthetics, Local/adverse effects · Anesthetics, Local/therapeutic use · Animals · Double-Blind Method · Horse Diseases/drug therapy · Horses · Ileus/drug therapy · Ileus/veterinary · Infusions, Intravenous/veterinary · Length of Stay · Lidocaine/adverse effects · Lidocaine/therapeutic use · Postoperative Complications/epidemiology · Postoperative Complications/veterinary · Prospective Studies · Safety · Treatment Outcome

Brianceau 2002: perioperative lidocaine improved jejunal ultrasound measures and abolished detectable peritoneal fluid, but did not change gastric reflux, first faeces or outcome

Randomised controlled study (record's own wording: horses 'were randomly assigned'); publication type: Clinical Trial — no blinding stated in the record

Who: Horses: 28 horses with the diagnosis of an intestinal disorder requiring surgical intervention, randomly assigned to lidocaine (n = 13) or saline (control, n = 15) treatment groups. After induction of anesthesia, treated horses received a loading dose of 2% lidocaine (0.65 mg/kg) intravenously, followed by a continuous rate infusion of 1% lidocaine (0.025 mg/kg/min) until the discontinuation of anesthesia; upon recovery, a 2nd loading dose of 2% lidocaine (1.3 mg/kg) was administered, followed by an infusion of 1% lidocaine (0.05 mg/kg/min) for 24 hours postoperatively. The control group received equivalent volumes of saline.

Result: Lidocaine-treated horses had significantly better minimum jejunal cross-sectional area scores (P = .011), minimum jejunal diameter scores (P = .002), and intestinal ultrasound index (IUI) (P = .007). Peritoneal fluid was detected by percutaneous ultrasound examination in 8 of the 15 control animals but in none of the treated animals (P = .003). Failure to obtain fluid via abdominocentesis was significantly more frequent for lidocaine-treated horses (P = .025). No significant differences between the groups were found in the presence of gastrointestinal sounds, time to passage of 1st feces, number of defecations in the 1st 24 hours, presence of gastric reflux, duodenal or jejunal wall thickness, maximum duodenal or jejunal diameter or cross-sectional area, minimum duodenal diameter or cross-sectional area, duodenal and jejunal intraluminal echogenicity, small-intestinal contractions per minute, rate of complications, or outcome.

Watch out: The significant benefits are ultrasound surrogates (jejunal distension scores and peritoneal fluid detection), not ileus duration or reflux: on the clinical ileus measures this trial was null, and the authors themselves note the low incidence of small-intestinal lesions and gastric reflux makes it difficult to assess lidocaine in the prevention of postoperative ileus (POI). The record does not state blinding, and none is claimed here.

Brianceau P, Chevalier H, Karas A, Court MH, Bassage L, Kirker-Head C, Provost P, Paradis MR. Intravenous lidocaine and small-intestinal size, abdominal fluid, and outcome after colic surgery in horses. Journal of veterinary internal medicine. 2002;16(6):736-41. PMID: 12465774. Registry ID: none in the record. MeSH: Abdominal Pain/etiology · Abdominal Pain/veterinary · Anesthesia, General/veterinary · Anesthetics, Local/administration & dosage · Anesthetics, Local/pharmacology · Animals · Ascitic Fluid · Colic/surgery · Colic/veterinary · Female · Gastrointestinal Motility · Horse Diseases/surgery · Horses · Infusions, Intravenous · Jejunum/anatomy & histology · Jejunum/pathology · Lidocaine/administration & dosage · Lidocaine/pharmacology · Male · Postoperative Complications/veterinary

Torfs 2009: prophylactic lidocaine was associated with lower odds of post-operative ileus (OR 0.25) and enhanced short-term survival (OR 0.30) in 126 small-intestinal colic surgery horses

Retrospective cross-sectional study (record's own wording)

Who: Horses: 126 horses that underwent small intestinal colic surgery and that survived for at least 24 hours postoperatively, in a retrospective cross-sectional study investigating the association of 31 pre-, intra-, and postoperative variables with post-operative ileus (POI) and the association of lidocaine treatment with short-term survival, evaluated with univariable logistic regression models followed by multivariable analysis.

Result: Prophylactic lidocaine treatment was significantly associated with a reduced incidence of POI (odds ratio [OR] = 0.25, 95% confidence interval [CI] 0.11-0.56) — a relative odds measure; the record reports no absolute ileus rates by treatment group alongside it. Lidocaine treatment was also significantly associated with enhanced short-term survival (OR = 0.30, 95% CI 0.09-0.98). Variables associated with an increased probability of POI were high heart rate (OR = 1.05, 95% CI 1.03-1.08), the presence of more than 8 L of reflux at admission (OR = 3.02, 95% CI 1.13-8.02) and the performance of a small intestinal resection (OR = 2.46, 95% CI 1.15-5.27).

Watch out: Retrospective and non-randomised: lidocaine was given by clinician choice, so these associations are open to confounding by indication and by treatment era, and an odds ratio is not an absolute reduction in ileus or death. This record supports the hypothesis; it cannot carry the claim on its own, and its survival association was not reproduced in the larger Salem 2016 cohort below.

Torfs S, Delesalle C, Dewulf J, Devisscher L, Deprez P. Risk factors for equine postoperative ileus and effectiveness of prophylactic lidocaine. Journal of veterinary internal medicine. 2009;23(3):606-11. PMID: 19422470. Registry ID: none in the record. MeSH: Animals · Colic/surgery · Colic/veterinary · Cross-Sectional Studies · Female · Gastrointestinal Agents/administration & dosage · Gastrointestinal Agents/therapeutic use · Horse Diseases/drug therapy · Horse Diseases/prevention & control · Horses · Intestinal Pseudo-Obstruction/complications · Intestinal Pseudo-Obstruction/pathology · Intestinal Pseudo-Obstruction/prevention & control · Intestinal Pseudo-Obstruction/veterinary · Intestine, Small/pathology · Lidocaine/administration & dosage · Lidocaine/therapeutic use · Male · Multivariate Analysis · Postoperative Complications/pathology · Postoperative Complications/prevention & control · Postoperative Complications/veterinary · Postoperative Period · Retrospective Studies · Risk Factors

Salem 2016: in 318 horses after small-intestinal colic surgery, perioperative lidocaine had no effect on reflux prevalence, volume or duration, or on post-operative survival

Analysis of data from two prospective studies (record's own wording); publication types from the record's indexing include Prospective Studies — lidocaine exposure was not randomised

Who: Horses: 318 horses undergoing surgical management of small intestinal lesions for treatment of colic at a UK equine referral hospital, with data collected as part of two prospective studies investigating postoperative survival of surgical colic patients admitted during 2004-2006 and 2012-2014, comparing horses that did or did not receive perioperative lidocaine (lidocaine exposure was not randomised).

Result: Data from 318 horses were included in the final analysis. The overall prevalence of postoperative reflux was 24.5%, significantly higher (34.8%) in horses admitted in 2012-2014 compared to the 2004-2006 cohort (16.7%). Perioperative lidocaine treatment had no effect on total reflux volume, duration of reflux or rates of postoperative survival, nor was it a risk factor associated with altered postoperative survival. Variables associated with increased risk of postoperative mortality included packed cell volume on admission (hazard ratio [HR] 1.03, 95% CI 1.004-1.06, p = 0.024), heart rate on admission (HR 1.014, 95% CI 1.004-1.024, p = 0.008) and duration of surgery (HR 1.007, 95% CI 1.002-1.01, p = 0.008). The authors concluded that a well-designed multicentre, prospective randomised controlled trial is needed.

Watch out: Lidocaine use was not randomised in this analysis, and reflux prevalence differed markedly between the two admission eras (16.7% vs 34.8%), so era and case-mix confounding could mask or mimic an effect in either direction. It is nonetheless the largest carded population, and its null result on the same reflux and survival outcomes Malone measured is the main reason the overall evidence is graded as split rather than positive.

Salem SE, Proudman CJ, Archer DC. Has intravenous lidocaine improved the outcome in horses following surgical management of small intestinal lesions in a UK hospital population? BMC veterinary research. 2016;12(1):157. PMID: 27459996. Registry ID: none in the record. MeSH: Administration, Intravenous · Anesthetics, Local/administration & dosage · Animals · Colic/drug therapy · Colic/surgery · Colic/veterinary · Gastroesophageal Reflux/prevention & control · Gastroesophageal Reflux/veterinary · Horse Diseases/drug therapy · Horse Diseases/surgery · Horses · Intestine, Small/pathology · Intestine, Small/surgery · Kaplan-Meier Estimate · Lidocaine/administration & dosage · Postoperative Complications/prevention & control · Prospective Studies · Risk Factors · Treatment Outcome

Synthesis: a small blinded RCT says lidocaine stops reflux sooner; the largest cohort says it changes neither reflux nor survival — the question is unresolved

Synthesis

Who: Synthesis of the cards above: Malone 2006 (32 refluxing horses with POI or enteritis, prospective double-blinded placebo-controlled trial), Brianceau 2002 (28 colic-surgery horses, randomly assigned to perioperative lidocaine or saline), Torfs 2009 (126 small-intestinal colic surgery horses, retrospective cross-sectional) and Salem 2016 (318 small-intestinal colic surgery horses from two prospective studies, non-randomised lidocaine comparison).

Result: (1) Reflux cessation in established ileus: 65% (11/17) on lidocaine versus 27% (4/15) on saline stopped refluxing within 30 hours (Malone). (2) Perioperative prophylaxis outcomes: no significant difference in gastric reflux, first feces, complications or outcome in the randomised trial (Brianceau), despite better jejunal ultrasound scores and no detectable peritoneal fluid (8/15 controls vs 0/13 treated had fluid detected; P = .003). (3) Ileus incidence and survival in observational data point both ways: prophylactic lidocaine was associated with reduced POI odds (OR 0.25, 95% CI 0.11-0.56, relative) and enhanced short-term survival in 126 horses (Torfs), but lidocaine had no effect on reflux volume, reflux duration or survival in 318 horses (Salem). (4) Safety in the blinded trial: no difference in incisional infections, jugular thrombosis, laminitis or diarrhea; muscle fasciculations in 3 of 17 lidocaine horses (18%) (Malone).

Watch out: Treatment of established ileus (Malone) and perioperative prophylaxis (the other three cards) are different uses, and the two observational cards disagree with each other as well as with the small blinded trial. Until a large multicentre randomised trial is done, neither routine use nor abandonment is evidence-settled; survival was equivalent in the one blinded trial and unaffected in the largest cohort, so no survival claim is supported.

Synthesis of Malone E et al. PMID: 16409411; Brianceau P et al. PMID: 12465774; Torfs S et al. PMID: 19422470; Salem SE et al. PMID: 27459996. Registry IDs as on the individual cards.

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