VetMedOvariohysterectomy in dogs: does maropitant reduce postoperative visceral pain? — POSSIBLE (the treatment made no difference to postoperative pain scores)
In dogs undergoing ovariohysterectomy, does maropitant vs placebo reduce postoperative visceral pain scores and rescue analgesia?
Shelf #527 · gate-verified and displayed under the developer's blinded-trial rule
POSSIBLE (the treatment made no difference to postoperative pain scores): In clinical ovariohysterectomy trials, maropitant lowered intraoperative inhalant requirements but did not improve postoperative pain scores against saline/placebo controls. Swallow 2017 (randomised, blinded, saline-controlled, 24 dogs, on methadone + meloxicam): overall end-tidal isoflurane was 1.19±0.26% with maropitant vs 1.44±0.23% with saline (p=0.022), but postoperative Glasgow pain scores did not differ between groups. E Silva 2025 (randomised, saline continuous-infusion control, 45 dogs, four maropitant infusion doses): no significant differences in postoperative pain evaluation at any dose; expired sevoflurane was lower at 50 and 100 µg/kg/hour (1.81±0.07 and 1.81±0.06 vs 2.11±0.07). One smaller randomised trial without a placebo arm (Bozkurt 2024, 36 bitches) reported lower University of Melbourne pain scores with maropitant than with meloxicam or a control group (p<0.05, no numeric scores in the record), and an experimental study (Boscan 2011, 8 dogs) showed maropitant cut sevoflurane MAC during ovarian traction by 24% at the low dose and 30% at the high dose — visceral antinociception under anaesthesia, not postoperative pain relief. Design class (a): randomisation and blinding are both established by a carded record — Swallow 2017 randomly assigned dogs, used observers unaware of group allocation and blinded postoperative assessors, and carries publication type Randomized Controlled Trial. The honest limits: the two saline-controlled trials gave all dogs opioid ± NSAID analgesia, so they test maropitant as an add-on, not alone; Bozkurt's control-group treatment is not described in its record and it reports no numeric pain scores; and rescue-analgesia counts were not reported as an outcome in the saline-controlled trials. Drafted Nov 10, 2026 (VetMed build, topic #527); all figures from records fetched and verified at drafting.
Swallow 2017: maropitant cut overall isoflurane requirement (1.19% vs 1.44%) but postoperative Glasgow pain scores did not differ from saline in 24 dogs having ovariohysterectomy
Randomized clinical trial, saline placebo control, blinded postoperative assessment (record's own wording: 'Randomized clinical trial'; anaesthetist 'unaware of group allocation' and postoperative assessors 'blinded observers'; publication type: Randomized Controlled Trial)
Who: Dogs: 24 healthy client-owned dogs undergoing routine ovariohysterectomy. All dogs were premedicated with acepromazine (0.03 mg/kg) combined with methadone (0.3 mg/kg) intramuscularly, induced with intravenous propofol and given intravenous meloxicam (0.2 mg/kg), and were randomly assigned to subcutaneous saline (0.1 mL/kg, n=12) or maropitant (1 mg/kg, n=12) at the time of premedication; methadone (0.1 mg/kg IV) was repeated 4 hours later. Anaesthesia was maintained with isoflurane in oxygen, dosed to effect by an observer unaware of group allocation.
Result: Overall mean±standard deviation end-tidal isoflurane percentage was lower in the maropitant group (1.19±0.26%) than the saline group (1.44±0.23%) (p=0.022), but was not significantly different between groups at specific noxious events (skin incision, ovarian pedicle clamp application, cervical clamp application, wound closure). Postoperative short-form Glasgow Composite Pain Scores, assessed hourly starting 1 hour postoperatively by blinded observers, were not significantly different between groups. Overall, 50% of dogs displayed signs attributable to postoperative nausea and vomiting, with no difference in those scores between groups (p=0.198), and owners noted no difference in anaesthetic recovery.
Watch out: Every dog received methadone and meloxicam, so this trial tests maropitant as an add-on to standard analgesia, not as a sole analgesic; the authors' own clinical-relevance statement is that maropitant provided no significant benefits to dogs undergoing ovariohysterectomy with this protocol. Rescue-analgesia use is not reported in the record.
Swallow A, Rioja E, Elmer T, Dugdale A. The effect of maropitant on intraoperative isoflurane requirements and postoperative nausea and vomiting in dogs: a randomized clinical trial. Vet Anaesth Analg. 2017;44(4):785-793. PMID: 28844293. Registry ID: none in the record. MeSH: Anesthesia, Inhalation/adverse effects, methods, veterinary* · Anesthetics, Inhalation/administration & dosage* · Animals · Antiemetics/therapeutic use* · Dog Diseases/prevention & control* · Dogs · Female · Hysterectomy/veterinary · Isoflurane/administration & dosage* · Ovariectomy/veterinary · Postoperative Nausea and Vomiting/prevention & control, veterinary* · Quinuclidines/therapeutic use*
E Silva 2025: no dose of maropitant infusion changed postoperative pain evaluation versus saline in 45 dogs, though two doses lowered expired sevoflurane
Prospective randomized clinical study, saline continuous-infusion control (record's own wording: 'a prospective randomized clinical study'; publication type: Randomized Controlled Trial; blinding not stated in the record)
Who: Dogs: 45 healthy female dogs undergoing ovariohysterectomy, randomly assigned to five groups of 9. All groups received morphine and acepromazine premedication, propofol induction and sevoflurane maintenance. The control group received a continuous rate infusion (CRI) of 0.9% saline at 1 mL/kg/hour; the treatment groups received an intravenous bolus of maropitant 1 mg/kg followed by a CRI of 50, 75, 100 or 200 µg/kg/hour. Postoperative pain was assessed with the Short Form Glasgow Composite Measure Pain Scale, with tramadol rescue analgesia when the score was >6; intraoperative fentanyl rescue was given when heart rate and blood pressure increased by >20%.
Result: There were no significant differences between groups in cardiorespiratory parameters, temperature or postoperative pain evaluation. Expired fraction of sevoflurane differed: control 2.11±0.07 versus 1.81±0.07 at 50 µg/kg/hour (p<0.04) and 1.81±0.06 at 100 µg/kg/hour (p<0.03). The authors conclude that maropitant CRI lowered sevoflurane requirements at those doses but was not sufficient to suppress the autonomic response to somatic and visceral nociceptive stimulation and did not demonstrate any evident effect on pain evaluation.
Watch out: Blinding of the pain assessors is not stated in this record and none is claimed for it; the shelf's blinding basis comes from Swallow 2017. The record reports pain-scale evaluation, not per-group rescue tramadol counts, so no rescue-analgesia comparison can be drawn from it.
E Silva AK, Castro ML, Fagundes N, Wenceslau RR, Malm C, de Sousa FG, Mattoso CRS, Beier SL. Evaluation of the antinociceptive effect of NK-1 antagonist - maropitant, in different doses in dogs undergoing ovariohysterectomy - a prospective randomized clinical study. Vet Res Commun. 2025;50(1):17. PMID: 41174265. Registry ID: none in the record. MeSH: Animals · Dogs/surgery · Female · Analgesics*/administration & dosage, therapeutic use, pharmacology · Dose-Response Relationship, Drug · Hysterectomy*/adverse effects, veterinary · Neurokinin-1 Receptor Antagonists*/administration & dosage, therapeutic use, pharmacology · Ovariectomy*/adverse effects, veterinary · Postoperative Pain*/veterinary, drug therapy, prevention & control · Prospective Studies · Quinuclidines*/administration & dosage, therapeutic use, pharmacology
Bozkurt 2024: University of Melbourne pain scores were lower with maropitant than with meloxicam or control (p<0.05) in 36 bitches — but the record gives no numeric scores
Randomized controlled trial versus meloxicam and a control group (publication type: Randomized Controlled Trial; record states bitches were 'randomly divided'; blinding not stated in the record)
Who: Dogs: 36 bitches undergoing ovariohysterectomy, randomly divided into maropitant, meloxicam and control groups. Heart rate, peripheral oxygen saturation and respiratory rate were monitored during the procedure; pain scores were assessed using the University of Melbourne Pain Scale; blood samples were collected before anaesthesia induction and 24 hours after the operation for C-reactive protein. The record does not describe what the control group received.
Result: The pain scores of the maropitant group were significantly lower than those of the other groups (p<0.05); no numeric pain scores are given in the record. When the right ovary was removed, heart rate did not differ between the control and meloxicam groups, and heart rate in the maropitant group was significantly lower than in the control group (p<0.05). Rescue analgesia was not necessary for any bitch at any time point, and no significant differences in C-reactive protein levels were observed between groups. The authors conclude that, compared with meloxicam, maropitant provided more effective visceral analgesia, with no significant difference in anti-inflammatory effect.
Watch out: This is the one clinical trial here favouring maropitant for postoperative pain, and it is also the least completely reported: no numeric pain scores, no stated blinding, and an undescribed control treatment, in a setting the authors frame around injectable anaesthetics such as ketamine and xylazine being commonly used in developing countries. Its result is not reproduced by the two saline-controlled trials on this shelf, which used opioid/NSAID background analgesia.
Bozkurt G, Kaya F, Yildiz M. Does maropitant provide more effective perioperative pain management than meloxicam in bitches undergoing ovariohysterectomy? The first report on the comparison of visceral algesia-analgesia for ovariohysterectomy. Res Vet Sci. 2024;169:105179. PMID: 38335894. Registry ID: none in the record. MeSH: Female · Dogs · Animals · Meloxicam/therapeutic use · Pain Management/veterinary · Ovariectomy/adverse effects, veterinary · Ketamine* · Postoperative Pain/drug therapy, prevention & control, veterinary · Hysterectomy/veterinary · Analgesia*/veterinary · Anti-Inflammatory Agents/therapeutic use · Dog Diseases* · Quinuclidines*
Boscan 2011: during ovarian traction in 8 anaesthetised dogs, maropitant lowered sevoflurane MAC by 24% at the low dose and 30% at the high dose
Experimental within-dog study under anaesthesia (no randomisation or blinding stated in the record; publication type is not Randomized Controlled Trial)
Who: Dogs: 8 one-year-old female dogs anaesthetised with sevoflurane in a laboratory setting. Following instrumentation, the right ovary and ovarian ligament were accessed by laparoscopy and the ovary was stimulated with a traction force of 6.61 N; the minimum alveolar concentration (MAC) of sevoflurane was determined before and after two doses of maropitant.
Result: The sevoflurane MAC value during stimulation without treatment (control) was 2.12±0.4%. Maropitant 1 mg/kg IV followed by 30 µg/kg/h IV decreased MAC to 1.61±0.4% (a 24% decrease), and a higher dose (5 mg/kg IV followed by 150 µg/kg/h IV) decreased MAC to 1.48±0.4% (a 30% decrease). The authors conclude that maropitant decreased anaesthetic requirements during visceral stimulation of the ovary and ovarian ligament, suggesting a potential role for neurokinin-1 receptor antagonists in managing ovarian and visceral pain.
Watch out: This is an anaesthetic-requirement (MAC) experiment during a standardised visceral stimulus, not a clinical postoperative pain trial: no postoperative pain scores, no rescue analgesia, and no placebo group — each dog served as its own control across doses. It supports visceral antinociception under anaesthesia, which the clinical trials above did not convert into better postoperative pain scores.
Boscan P, Monnet E, Mama K, Twedt DC, Congdon J, Steffey EP. Effect of maropitant, a neurokinin 1 receptor antagonist, on anesthetic requirements during noxious visceral stimulation of the ovary in dogs. Am J Vet Res. 2011;72(12):1576-9. PMID: 22126683. Registry ID: none in the record. MeSH: Anesthesia, Inhalation/veterinary · Anesthetics, Inhalation/administration & dosage*, pharmacokinetics · Animals · Antiemetics/administration & dosage*, pharmacokinetics · Dogs/metabolism* · Female · Infusions, Intravenous/veterinary · Laparoscopy/veterinary · Ligaments/physiopathology · Methyl Ethers/administration & dosage*, pharmacokinetics · Neurokinin-1 Receptor Antagonists* · Ovary/physiopathology · Pulmonary Alveoli/metabolism · Quinuclidines/administration & dosage*, pharmacokinetics · Sevoflurane · Visceral Pain/prevention & control, veterinary*
Synthesis: maropitant spares inhalant during visceral stimulation but has not beaten saline on postoperative pain scores after ovariohysterectomy — POSSIBLE (the treatment made no difference to postoperative pain scores)
Synthesis
Who: Synthesis of the cards above: Swallow 2017 (randomised, blinded, saline-controlled trial, 24 dogs, methadone + meloxicam background), E Silva 2025 (randomised saline-controlled infusion trial, 45 dogs, four maropitant doses), Bozkurt 2024 (randomised trial, 36 bitches, maropitant vs meloxicam vs control) and Boscan 2011 (experimental MAC study, 8 dogs, ovarian traction).
Result: Synthesis: (1) Against saline/placebo controls, postoperative pain scores did not differ: Swallow 2017 (blinded Glasgow scoring, opioid + NSAID on board) and E Silva 2025 (four infusion doses, Glasgow short-form scoring). (2) Intraoperative visceral antinociception is consistent: Boscan 2011 cut sevoflurane MAC during ovarian traction by 24–30%, and both saline-controlled clinical trials found lower inhalant requirements with maropitant (isoflurane 1.19% vs 1.44% overall in Swallow; expired sevoflurane 1.81% vs 2.11% at two infusion doses in E Silva). (3) The one trial reporting lower postoperative pain scores (Bozkurt 2024) had no placebo arm, no numeric scores in its record and an undescribed control group. On the carded evidence, maropitant added to standard analgesia should not be expected to reduce postoperative pain scores after ovariohysterectomy.
Watch out: Maropitant's antiemetic questions are homed elsewhere in the library and their claim-carrying records are not re-carded here: acute vomiting (Shelf #168), feline maropitant (Shelf #375), motion sickness (Shelf #397) and perioperative vomiting/reflux (Shelf #695). This shelf is only about postoperative visceral analgesia after ovariohysterectomy in dogs. None of the carded trials reports a mortality or survival outcome, and no rescue-analgesia advantage is demonstrated on this shelf.
Synthesis of Swallow A et al. PMID: 28844293; E Silva AK et al. PMID: 41174265; Bozkurt G et al. PMID: 38335894; Boscan P et al. PMID: 22126683. Registry IDs as on the individual cards.
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