Pre-anaesthetic omeprazole in dogs: does it reduce gastro-oesophageal reflux and oesophagitis vs placebo? — POSSIBLE

In dogs undergoing anaesthesia, does pre-anaesthetic omeprazole vs placebo reduce gastro-oesophageal reflux and oesophagitis?

Shelf #696 · gate-verified and approved by the developer

POSSIBLE: Pre-anaesthetic omeprazole reduces acidic reflux exposure in anaesthetised dogs, most consistently when two doses are given, but the two randomised trials disagree on whether it reduces how many dogs reflux at all, and neither trial measured oesophagitis — so the oesophagitis half of this shelf's question has no direct record. In Panti 2009 (PMID: 19796313; 47 dogs undergoing elective pelvic limb orthopaedic surgery, randomly allocated to one oral omeprazole dose of 1 mg/kg at least 4 hours before anaesthesia, n = 22, or control, n = 25), a sudden fall in distal oesophageal pH to below 4 occurred in 4 of 22 omeprazole dogs (18%) vs 13 of 25 control dogs (52%) — an absolute difference of 34 percentage points — and the record states gastro-oesophageal reflux occurred more frequently in the control group (odds ratio 4.7, 95% CI 1.1 to 24.7, P = 0.032, for control vs omeprazole as reported). In Lotti 2021 (PMID: 33769569; 55 dogs undergoing elective ovariectomy, randomly assigned to omeprazole 1 mg/kg orally once the evening before, n = 20, omeprazole twice — evening before and 3 hours before anaesthesia, n = 15, or no-omeprazole control, n = 20, with an oesophageal impedance/pH probe), reflux incidence did not differ significantly between groups: 55% (11/20) control, 55% (11/20) once, and 47% (7/15) twice. What did change was reflux acidity: mean reflux pH was higher with two doses (6.3 ± 1.5) than in controls (3.8 ± 1.1) or once-dosed dogs (4.1 ± 1.5), and strongly acidic reflux (pH < 4) occurred in 7% (1/15) of twice-dosed dogs vs 55% (11/20) of controls and 35% (7/20) of once-dosed dogs — an absolute reduction of 48 percentage points vs control for the two-dose protocol. A single evening-before dose had no effect on reflux pH in Lotti 2021, which tempers Panti 2009's single-dose result (whose dose was given at least 4 hours before anaesthesia, a different timing). Design class (b): randomisation is established by both carded records answering this shelf's own comparison (Panti: 'randomly allocated', with Random Allocation in its MeSH; Lotti: 'randomly assigned', publication type Randomized Controlled Trial, Veterinary), but neither record states masking/blinding — Panti's comparator is described only as a control group and Lotti's as a group that did not receive omeprazole, with no placebo described in either abstract — so class (a) is not claimed. The stamp is POSSIBLE, not LIKELY, because reflux incidence — the outcome closest to the question — was reduced in one trial and unchanged in the other, both trials are small, and oesophagitis itself (an endoscopic or clinical outcome) was measured in neither. One-home cross-points, not carded: esomeprazole is a different drug — Zacuto 2012 (PMID: 22489656; esomeprazole alone did not significantly decrease reflux frequency, P = 0.955, while esomeprazole plus cisapride did) does not carry an omeprazole claim. Garcia 2017 (PMID: 28425145) is the same omeprazole-vs-placebo design in CATS (gastric pH 7.2 ± 0.4 vs 2.8 ± 1.0, P < .001) and is not imported into a dog shelf. Shelf #400 (omeprazole vs famotidine, intragastric pH in healthy awake dogs) is a pH-only neighbouring question: its records do not measure reflux or oesophagitis under anaesthesia and are not re-carded here; shelves #694 (fasting duration) and #695 (maropitant) likewise answer different comparisons. Tier C is not engaged: no mortality or survival claim is made. Drafted Nov 10, 2026 (VetMed build, topic #696); figures from the abstracts, fetched and verified at drafting.

Panti 2009: one pre-anaesthetic omeprazole dose cut pH-defined reflux from 52% (13/25) in controls to 18% (4/22) in treated dogs (OR 4.7 for control vs omeprazole, P = 0.032)

Randomised controlled trial (record's own wording: 'randomly allocated'; MeSH includes Random Allocation; publication types: Journal Article, Research Support, Non-U.S. Gov't). Blinding/masking is not stated in the record.

Who: Dogs: 47 dogs undergoing elective pelvic limb orthopaedic surgery under a standardised anaesthetic protocol, randomly allocated to a treatment group (n = 22) receiving one dose of omeprazole 1 mg/kg orally at least 4 hours before anaesthesia, or a control group (n = 25) receiving no omeprazole (no placebo is described in the record). A pH probe in the distal oesophagus monitored oesophageal pH continuously after induction.

Result: In the treatment group, 4 animals (18%) showed a sudden decrease in oesophageal pH to below 4; in the control group the same phenomenon was detected in 13 animals (52%) — an absolute difference of 34 percentage points. The record states gastro-oesophageal reflux occurred more frequently in the control group compared with the omeprazole group (odds ratio 4.7, 95% CI 1.1 to 24.7, P = 0.032). The authors conclude preoperative omeprazole is effective in reducing the incidence of gastro-oesophageal reflux during anaesthesia in dogs. No endoscopic oesophagitis outcome was measured; reflux was defined by the oesophageal pH fall.

Watch out: Reflux here is a pH-probe definition (a sudden oesophageal pH fall below 4), not observed regurgitation and not oesophagitis — no dog's oesophagus was examined. The control group received no described placebo and no masking is stated, so class (b), not (a). The confidence interval on the odds ratio is very wide (1.1 to 24.7) on 47 dogs, and the single dose was timed at least 4 hours before anaesthesia, which differs from the evening-before single dose that showed no pH effect in Lotti 2021.

Panti A, Bennett RC, Corletto F, Brearley J, Jeffery N, Mellanby RJ. The effect of omeprazole on oesophageal pH in dogs during anaesthesia. J Small Anim Pract. 2009;50(10):540-4. PMID: 19796313. Registry ID: none in the record. MeSH: Anesthesia, General/adverse effects/veterinary* · Animals · Dogs · Esophageal pH Monitoring/veterinary* · Female · Gastroesophageal Reflux/drug therapy/epidemiology/prevention & control/veterinary* · Male · Omeprazole/therapeutic use* · Postoperative Complications/prevention & control/veterinary · Preoperative Care/methods/veterinary* · Proton Pump Inhibitors/therapeutic use* · Random Allocation · Treatment Outcome

Lotti 2021: omeprazole did not change reflux incidence (55% control, 55% once, 47% twice), but two doses raised reflux pH and cut strongly acidic reflux to 7% (1/15) vs 55% (11/20) in controls

Randomised controlled trial (record's own wording: 'randomly assigned'; publication type: Randomized Controlled Trial, Veterinary). Blinding/masking is not stated in the record.

Who: Dogs: 55 dogs undergoing elective ovariectomy, randomly assigned to omeprazole 1 mg/kg orally once the evening before anaesthesia (n = 20), omeprazole 1 mg/kg orally twice — the evening before and 3 hours before anaesthesia (n = 15), or a control group that did not receive omeprazole (n = 20; no placebo is described in the record). An oesophageal impedance/pH probe measured gastro-oesophageal reflux incidence and pH during anaesthesia.

Result: Gastro-oesophageal reflux was observed in 55% (11/20) of control dogs, 55% (11/20) of dogs receiving omeprazole once and 47% (7/15) of dogs receiving omeprazole twice; the incidence was not statistically significantly different between groups. Reflux pH (mean ± sd) was higher in dogs receiving omeprazole twice (6.3 ± 1.5) compared with control dogs (3.8 ± 1.1) or dogs receiving omeprazole once (4.1 ± 1.5). Strongly acidic reflux (pH < 4) was observed in 7% (1/15) of twice-dosed dogs vs 55% (11/20) of control dogs and 35% (7/20) of once-dosed dogs — an absolute reduction of 48 percentage points for two doses vs control. The authors conclude the two-dose protocol increased reflux pH and decreased strongly acidic reflux, while a single evening-before dose had no effect on reflux pH. No oesophagitis outcome was measured.

Watch out: The headline outcome of this shelf — reflux incidence — was a null in this trial, including for the two-dose arm (47% vs 55%); the benefit is in reflux acidity, a step removed from oesophagitis, which was not assessed. The twice-dosed arm is only 15 dogs, the control was an untreated group rather than a described placebo, and no masking is stated, so class (b). Elective ovariectomy patients only; reflux was measured by impedance/pH probe during anaesthesia, not by clinical signs after recovery.

Lotti F, Twedt D, Warrit K, Bryan S, Vaca C, Krause L, Fukushima K, Boscan P. Effect of two different pre-anaesthetic omeprazole protocols on gastroesophageal reflux incidence and pH in dogs. J Small Anim Pract. 2021;62(8):677-682. PMID: 33769569. Registry ID: none in the record. MeSH: Anesthetics* · Animals · Dog Diseases*/epidemiology · Dogs · Female · Gastroesophageal Reflux*/drug therapy/epidemiology/veterinary · Hydrogen-Ion Concentration · Incidence · Omeprazole/therapeutic use

Synthesis: omeprazole makes reflux less acidic (two doses) but does not reliably stop reflux happening, and oesophagitis prevention is unproven — POSSIBLE

Synthesis

Who: Synthesis of the two carded randomised trials above (Panti 2009, n = 47; Lotti 2021, n = 55) and of the near-miss records documented in the result, fetched at drafting and deliberately not carded as claim-carriers.

Result: (1) Reflux incidence: the trials conflict — Panti 2009 found 18% (4/22) with a single dose given at least 4 hours pre-anaesthesia vs 52% (13/25) in controls, while Lotti 2021 found 55%/55%/47% across control, once-dosed and twice-dosed groups with no significant difference. Dose timing is the visible difference between the single-dose results. (2) Reflux acidity: consistent direction — Lotti's two-dose protocol raised mean reflux pH to 6.3 ± 1.5 vs 3.8 ± 1.1 in controls and reduced strongly acidic reflux from 55% (11/20) to 7% (1/15). (3) Oesophagitis: neither trial examined the oesophagus, so any oesophagitis benefit is inference from reduced acid exposure, not a measured outcome. (4) Near-misses not carded: Zacuto 2012 (PMID: 22489656) tested esomeprazole, a different proton pump inhibitor, in 61 dogs — esomeprazole alone did not significantly decrease reflux frequency (8/22, 36%, vs 8/21, 38.1%, on placebo; P = 0.955 for the frequency comparison as reported) — and Garcia 2017 (PMID: 28425145) is the feline study (27 cats), a different species. (5) Design class (b): both carded trials are randomised and answer this shelf's own comparison in anaesthetised dogs, but neither record states masking and neither describes a placebo, so blinded class (a) is not claimed. POSSIBLE reflects a real, replicated acid-suppression effect on refluxate pH against an inconsistent incidence effect and an unmeasured clinical endpoint.

Watch out: One-home check at drafting: none of PMIDs 19796313, 33769569, 22489656 or 28425145 appears in any other pack on disk. Boundary honoured: shelf #400 homes the omeprazole-vs-famotidine intragastric-pH question in healthy awake dogs — a pH-only record does not carry this shelf's reflux/oesophagitis claim, and none of its records is re-carded here; shelves #694 (fasting) and #695 (maropitant) are different perioperative comparisons. Do not state that omeprazole prevents oesophagitis in dogs: no carded record measured oesophagitis.

Synthesis of Panti A et al. PMID: 19796313; Lotti F et al. PMID: 33769569; Zacuto AC et al. PMID: 22489656; Garcia RS et al. PMID: 28425145. Registry IDs as on the individual cards (none in the records).

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