Cats: does methadone premedication give better sedation and postoperative analgesia than buprenorphine? — POSSIBLE

In cats, does methadone vs buprenorphine premedication give better sedation and postoperative analgesia?

Shelf #746 · gate-verified and displayed under the developer's blinded-trial rule

POSSIBLE: In cats, methadone premedication gave better postoperative analgesia than buprenorphine in the largest head-to-head trial, but three smaller randomised blinded trials found mostly no difference (the treatment made no difference on most measures in those settings). In Shah 2019 (assessor-blinded, randomised clinical trial, 120 cats in the QUAD protocol — ketamine, midazolam and medetomidine plus either methadone 5 mg/m2 or buprenorphine 180 µg/m2 intramuscularly, for ovariohysterectomy), methadone cats had lower Composite Measure Pain Scale-Feline scores over time (P = 0.04) and fewer needed rescue analgesia: 18/60 (30.0%) versus 29/60 (48.3%) — an absolute difference of 18.3 percentage points, a 38% relative reduction in the proportion needing rescue (P = 0.028); there was no difference on mechanical nociceptive threshold or dynamic interactive visual analogue scale. By contrast, Mahdmina 2020 (51 cats recruited, 41 completed; medetomidine plus methadone or buprenorphine, then intramuscular alfaxalone) found only a lower dynamic interactive visual analogue scale score at 10 minutes post-extubation on methadone and no difference at any other time point on four instruments, with no cat needing rescue; Slingsby 2015 (assessor-blinded, randomised, 45 cats, medetomidine partner) found small differences at individual time points only and rescue in 2 methadone versus 0 buprenorphine cats, not significant; and Bortolami 2013 (block-randomised, prospective, blinded, 45 cats, acepromazine partner) found sedation scores, pain scores at all time points and rescue use were not statistically different between groups. Design class (a): the pivotal carded record (Shah 2019, PMID: 30215269) is randomised and assessor-blinded and answers this shelf's own comparison and population (cats, methadone vs buprenorphine premedication, ovariohysterectomy); the other carded trials are likewise randomised and blinded. Limits stated plainly: sedation — half the mined question — was measured in the carded trials but no carded abstract reports a significant sedation difference, and Shah 2019 reports no sedation result at all, so a sedation advantage for either drug is unanswered, not shown to be absent; the positive trial is a single specific protocol (QUAD, body-surface-area dosing) and its pain advantage appeared on one of three instruments; the null trials mixed ovariohysterectomy with castration and used different sedative partners and doses; and postoperative windows were short (30 minutes in Mahdmina, 8 hours in Shah, with further analgesia confounding later time points in Slingsby). One large positive protocol-specific trial against three smaller largely null trials supports POSSIBLE, not LIKELY. Cross-point, not re-carded: the same drug pair in dogs undergoing ovariohysterectomy homes on Shelf #521 and in rabbits on the pile topic #929 — different species and shelves. Drafted Nov 10, 2026 (VetMed build, topic #746); all figures from the abstract fetched and verified at drafting.

Shah 2019: methadone in the QUAD protocol gave lower pain scores (P = 0.04) and less rescue analgesia — 18/60 (30.0%) versus 29/60 (48.3%) on buprenorphine (P = 0.028) — in 120 cats undergoing ovariohysterectomy

Assessor-blinded, randomised clinical trial (record's own wording: 'an assessor-blinded, randomised clinical trial'; publication type: Randomized Controlled Trial, Veterinary) — note the record's MeSH also includes Double-Blind Method, but the abstract's own wording establishes assessor-blinding, and this card claims no more than that

Who: Cats: 120 female cats undergoing ovariohysterectomy in a clinical setting, recruited to an assessor-blinded, randomised clinical trial. Cats received either methadone (5 mg/m2) or buprenorphine (180 µg/m2) combined with ketamine, midazolam and medetomidine intramuscularly (the QUAD protocol). Anaesthesia was maintained with isoflurane in oxygen; atipamezole was administered at extubation. Pain was assessed using the feline Composite Measure Pain Scale (CMPS-F), a dynamic interactive visual analogue scale (DIVAS) and mechanical nociceptive threshold (MNT). Sedation, pain, heart rate and respiratory rate were measured prior to QUAD administration, before intubation, and 2, 4, 6 and 8 h post-QUAD administration. Rescue analgesia, if indicated by the CMPS-F, was methadone 0.5 mg/kg intramuscularly; meloxicam was administered after the last assessment.

Result: Cats administered methadone had lower CMPS-F scores over time (P = 0.04). Eighteen of 60 cats required rescue analgesia in the methadone group versus 29/60 in the buprenorphine group (P = 0.028) — 30.0% versus 48.3%, an absolute difference of 18.3 percentage points; the proportion needing rescue on methadone was 0.62 times that on buprenorphine, a 38% relative reduction. All cats that received rescue analgesia required it within 6 h post-QUAD administration. There were no differences between groups in MNT or pain measured using the DIVAS. The authors conclude methadone produced clinically superior postoperative analgesia for the first 8 h after neutering than buprenorphine when used within the QUAD protocol.

Watch out: Protocol-specific: the claim is methadone vs buprenorphine at body-surface-area doses (5 mg/m2 vs 180 µg/m2) inside one four-drug QUAD combination, not the opioids alone or at other doses. The pain advantage appeared on CMPS-F only — DIVAS and mechanical threshold showed no difference — and no sedation result is reported in the abstract, so this record does not answer the sedation half of the question. Follow-up was 8 hours, with meloxicam withheld until after the last assessment. A later record (PMID: 31532281) is a letter/comment on this trial, not a separate trial, and was not carded.

Shah M, Yates D, Hunt J, Murrell J. Comparison between methadone and buprenorphine within the QUAD protocol for perioperative analgesia in cats undergoing ovariohysterectomy. J Feline Med Surg. 2019;21(8):723-731. PMID: 30215269. Registry ID: none in the record. MeSH: Analgesia*/methods, veterinary · Analgesics, Opioid*/administration & dosage, therapeutic use · Animals · Buprenorphine*/administration & dosage, therapeutic use · Cats · Double-Blind Method · Drug Combinations · Female · Hysterectomy/adverse effects, methods*, veterinary · Methadone*/administration & dosage, therapeutic use · Ovariectomy/adverse effects, methods*, veterinary · Postoperative Pain/drug therapy, prevention & control, veterinary · Procedural Pain/drug therapy, prevention & control, veterinary

Mahdmina 2020: methadone vs buprenorphine with medetomidine and alfaxalone differed only on DIVAS at 10 minutes post-extubation — no difference at other time points on four instruments, and no cat needed rescue, in 41 completing cats

Randomised comparison with a blinded postoperative observer (record's own wording: cats 'were randomly allocated' and assessed 'by the same blinded observer'; publication type: Comparative Study)

Who: Cats: 51 female cats (American Society of Anesthesiologists status I-II), median age 12 months (range 2-60 months), mean ± SD weight 2.5 ± 0.5 kg, undergoing ovariohysterectomy in a clinical setting. Cats were randomly allocated to medetomidine (600 µg/m2) and buprenorphine (180 µg/m2) (group MB) or medetomidine (500 µg/m2) and methadone (5 mg/m2) (group MM) intramuscularly. Anaesthesia was induced 15 mins later using alfaxalone (3 mg/kg) intramuscularly and maintained with isoflurane in oxygen. All cats received meloxicam preoperatively. Atipamezole (50% of medetomidine dose) was administered at the end of surgery. Cats were assessed postoperatively by the same blinded observer using a simple descriptive scale, numeric rating scale, dynamic interactive visual analogue scale (DIVAS) and UNESP-Botucatu multidimensional composite pain scales, at 10, 20 and 30 mins post-extubation. Forty-one cats completed the study.

Result: No significant differences were detected between groups before or during anaesthesia. No cats required rescue analgesia. DIVAS scores at 10 mins were significantly less in the MM group compared with the MB group. No differences between groups at any other time points were detected using the four metrology instruments. The authors conclude both protocols provided good anaesthesia conditions for ovariohysterectomy in the cat.

Watch out: The postoperative window is only 10-30 minutes post-extubation — far too early and short to test postoperative analgesia over the hours that matter, and every cat had meloxicam on board, which can mask an opioid difference. Ten of 51 recruited cats did not complete the study, and the abstract does not report group sizes for the 41 completers or any absolute pain-score values. The single significant result is one instrument at one time point out of four instruments at three time points.

Mahdmina A, Evans A, Yates D, White KL. Comparison of the effects of buprenorphine and methadone in combination with medetomidine followed by intramuscular alfaxalone for anaesthesia of cats undergoing ovariohysterectomy. J Feline Med Surg. 2020;22(2):77-83. PMID: 30719951. Registry ID: none in the record. MeSH: Animals · Buprenorphine*/administration & dosage, therapeutic use · Cats · Central Nervous System Depressants*/administration & dosage, therapeutic use · Female · Hysterectomy/veterinary · Injections, Intramuscular · Medetomidine*/administration & dosage, therapeutic use · Methadone*/administration & dosage, therapeutic use · Ovariectomy/veterinary · Pain/drug therapy, veterinary · Pregnanediones*/administration & dosage, therapeutic use

Slingsby 2015: methadone vs buprenorphine with medetomidine — small pain differences at individual time points only, rescue in 2 versus 0 cats (not significant), in an assessor-blinded randomised study of 45 cats undergoing neutering

Assessor-blinded, randomised, clinical research study (record's own wording; publication type: Journal Article)

Who: Cats: 45 healthy cats recruited to an assessor-blinded, randomised, clinical research study, divided into three treatment groups of 15. Following premedication with medetomidine (20 µg/kg) and one of the three test drugs — methadone 0.5 mg/kg, buprenorphine 20 µg/kg or butorphanol 0.4 mg/kg intramuscularly — anaesthesia was induced with propofol and maintained with isoflurane, and neutering (ovariohysterectomy or castration) was carried out. Sedation and physiological parameters were assessed before premedication, after premedication before induction, and at 90 mins and 2, 3, 4, 6, 7, 8 and 24 h after premedication. Pain and mechanical nociceptive threshold were assessed at similar time points.

Result: There were no differences between groups with respect to age, sex, duration of anaesthesia or surgery. Most cats had low pain scores in the postoperative period, with small differences in pain scores between groups at individual time points only. Five, two and no cats required additional rescue analgesia in the postoperative period in the butorphanol, methadone and buprenorphine groups, respectively, representing no significant difference between groups — for the methadone vs buprenorphine comparison, 2/15 versus 0/15. The authors conclude medetomidine combined with methadone provided adequate analgesia for the first 6 h after administration with no adverse effects, with effects overall comparable with medetomidine combined with buprenorphine or butorphanol; administration of further analgesia with methadone at 6 h and a non-steroidal anti-inflammatory drug at 8 h provided adequate analgesia for the first 24 h after surgery.

Watch out: Mixed population: male castrations and female ovariohysterectomies are pooled, so the result is not ovariohysterectomy-specific, and groups are only 15 cats. Later time points are confounded by design — all cats were offered further methadone at 6 h and an NSAID at 8 h — and pain scores were low in all groups, leaving little room to detect a difference. The rescue counts (2 versus 0) are too small to support any claim in either direction.

Slingsby LS, Bortolami E, Murrell JC. Methadone in combination with medetomidine as premedication prior to ovariohysterectomy and castration in the cat. J Feline Med Surg. 2015;17(10):864-72. PMID: 25406177. Registry ID: none in the record. MeSH: Analgesia/veterinary · Analgesics, Opioid/administration & dosage* · Anesthesia, General/veterinary* · Animals · Cat Diseases/drug therapy, surgery* · Cats · Drug Therapy, Combination · Female · Hysterectomy/veterinary · Male · Medetomidine/administration & dosage* · Methadone/administration & dosage* · Orchiectomy/veterinary · Ovariectomy/veterinary · Pain/drug therapy, veterinary* · Premedication/veterinary*

Bortolami 2013: methadone vs buprenorphine with acepromazine — sedation scores, pain scores at all time points and rescue use were not statistically different (the treatment made no difference on those measures) in 45 cats undergoing neutering

Controlled clinical, block randomized, prospective, blinded study (record's own wording; publication type: Journal Article)

Who: Cats: 24 female and 21 male healthy cats in a controlled clinical, block randomized, prospective, blinded study designed for regulatory purposes. Cats received one of three opioids combined with acepromazine (0.05 mg/kg) intramuscularly for premedication: group 1 buprenorphine (0.02 mg/kg), group 2 methadone (0.5 mg/kg), group 3 butorphanol (0.4 mg/kg). Sedation was assessed 30 minutes after premedication using a visual analogue scale and simple descriptive scale. Anaesthesia was induced with alfaxalone and maintained with isoflurane in oxygen. Surgical ovariohysterectomy or castration was performed. Pain was assessed using an interactive visual analogue scale (IVAS) and mechanical nociceptive threshold (MNT). Methadone (0.5 mg/kg intramuscularly) and meloxicam (0.2 mg/kg subcutaneously) were provided 6 and 8 hours after premedication respectively, or together as rescue analgesia (IVAS above 50).

Result: Sedation scores, induction agent dose, pain scores at all time points and rescue analgesia were not statistically different between groups. In methadone treated cats there was no significant variation in MNT over time, suggesting a possible anti-hyperalgesic action, whereas in the other two groups lower thresholds were recorded at various time points after surgery compared to baseline. No cats required rescue analgesia after the second dose of methadone. No perioperative adverse effects occurred. The authors conclude methadone provided comparable sedation and analgesia to both buprenorphine and butorphanol when combined with acepromazine, and that differences in analgesic efficacy between opioids might have been undetectable because of the surgical model and surgeon competency.

Watch out: Mixed ovariohysterectomy and castration population, three arms of about 15 cats, and an acepromazine (not medetomidine or QUAD) partner — a different protocol family from Shah 2019 and Mahdmina 2020. The MNT finding is a within-group pattern over time, not a significant between-group difference, and the authors themselves flag that the surgical model may have been unable to detect efficacy differences. As with the other trials, no absolute sedation or pain values are given in the abstract.

Bortolami E, Murrell JC, Slingsby LS. Methadone in combination with acepromazine as premedication prior to neutering in the cat. Vet Anaesth Analg. 2013;40(2):181-93. PMID: 22731882. Registry ID: none in the record. MeSH: Acepromazine/administration & dosage, pharmacology* · Analgesics, Opioid/administration & dosage, pharmacology · Anesthesia, General/veterinary · Animals · Behavior, Animal · Buprenorphine/administration & dosage, pharmacology · Butorphanol/administration & dosage, pharmacology · Cats* · Dopamine Antagonists/administration & dosage, pharmacology · Drug Therapy, Combination · Female · Hysterectomy/veterinary* · Male · Methadone/administration & dosage, pharmacology* · Orchiectomy/veterinary* · Ovariectomy/veterinary* · Pain/prevention & control

Synthesis: methadone beat buprenorphine in the one large QUAD-protocol trial, while three smaller randomised blinded trials found mostly no difference — POSSIBLE; a sedation advantage for either drug is unanswered

Synthesis

Who: Synthesis of the cards above: Shah 2019 (120 cats, QUAD protocol, ovariohysterectomy, 8-hour follow-up), Mahdmina 2020 (41 completing cats, medetomidine/alfaxalone, 30-minute postoperative window), Slingsby 2015 (45 cats, medetomidine partner, mixed neutering) and Bortolami 2013 (45 cats, acepromazine partner, mixed neutering).

Result: (1) Largest trial: CMPS-F scores lower on methadone over time (P = 0.04) and rescue analgesia 18/60 (30.0%) versus 29/60 (48.3%) on buprenorphine (P = 0.028), with no difference on DIVAS or mechanical threshold (Shah). (2) Smaller trials: no difference except DIVAS at 10 minutes only (Mahdmina), small differences at individual time points only with rescue 2 versus 0 (Slingsby), and no statistically significant difference in sedation, pain or rescue (Bortolami). (3) Sedation: measured but never reported as significantly different in any carded abstract, and not reported at all in Shah — unanswered, not answered negatively. (4) No carded trial follows pain beyond 8 hours on the randomised comparison alone.

Watch out: A secondary knowledge summary (Lawrence 2024, PMID: 42004291) reviewing four assessor-blinded randomised trials reached a similar cautious conclusion ('may provide better analgesia'; more evidence needed) but was not carded as a claim-carrier, because it is a synthesis of the primary trials carded here. Experimental threshold studies in non-surgical cats (e.g. PMID: 17083457, subcutaneous opioids and thermal/pressure thresholds in 8 cats) were not carded — they do not test premedication for surgery. One-home note: the dog ovariohysterectomy comparison is Shelf #521 (PMID: 29781530, desk-checked, not re-carded here), and no record from that shelf or from any rabbit shelf is used here.

Synthesis of Shah M et al. PMID: 30215269; Mahdmina A et al. PMID: 30719951; Slingsby LS et al. PMID: 25406177; Bortolami E et al. PMID: 22731882. Registry IDs as on the individual cards.

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