Dexmedetomidine vs lidocaine infusion for inhalant sparing in dogs — POSSIBLE

In anaesthetised dogs, does a dexmedetomidine infusion vs a lidocaine infusion reduce inhalant requirement and improve recovery?

Shelf #532 · gate-verified and displayed under the developer's blinded-trial rule

POSSIBLE: Both infusions spare inhalant, and the two experimental minimum alveolar concentration (MAC) crossover studies found dexmedetomidine spared more than lidocaine at the doses tested, while the one randomised blinded clinical trial found the two nearly equal. Acevedo-Arcique 2014 (PMID: 25232737; 7 healthy dogs, crossover) found isoflurane MAC reduced by 43.4% (range 33.3-53.3%) on dexmedetomidine (2 µg/kg loading, 2 µg/kg/hour) and by 27.3% (12.5-39.2%) on lidocaine (2 mg/kg loading, 100 µg/kg/minute), with the combination reducing MAC by 60.9%. El-Hawari 2022 (PMID: 35698808; 6 Beagles, crossover) found sevoflurane MAC sparing of 40.3 ± 15.1% on dexmedetomidine (2 µg/kg, then 2 µg/kg/hour) versus 12.7 ± 14.3% on lidocaine (2 mg/kg, then 3 mg/kg/hour). Gutierrez-Blanco 2013 (PMID: 23910822; 54 dogs undergoing ovariohysterectomy, randomised, prospective, blinded) found overall end-tidal isoflurane of 1.30 ± 0.28 (24.8% reduction) on dexmedetomidine (1 µg/kg, then 3 µg/kg/hour) versus 1.34 ± 0.19 (22.5% reduction) on lidocaine (2 mg/kg, then 100 µg/kg/minute), against 1.73 ± 0.18 on the butorphanol/saline control — fentanyl and the lidocaine-ketamine-dexmedetomidine combination significantly reduced end-tidal isoflurane and, at the doses administered, had a greater isoflurane-sparing effect than lidocaine, ketamine or the control, but not at all times; no superiority over dexmedetomidine is reported. No carded record reports a recovery-quality advantage for either infusion: time to extubation and sternal recumbency did not differ among treatments in the dexmedetomidine-versus-combination MAC study cross-pointed in the synthesis (PMID: 23802667), and the carded trials do not compare recovery between dexmedetomidine and lidocaine infusions, so the recovery half of the question is unanswered. Design class (a): randomisation and blinding are established by a carded record answering the shelf's own comparison and population (Gutierrez-Blanco 2013, randomised prospective blinded clinical study with dexmedetomidine and lidocaine infusion arms). The stamp is POSSIBLE, not higher, because the MAC studies are very small (6-7 dogs), use different doses and inhalants, and disagree with the clinical trial on whether dexmedetomidine spares more than lidocaine. Drafted Nov 10, 2026 (VetMed build, topic #532); all figures from the abstracts fetched and verified at drafting.

Acevedo-Arcique 2014: dexmedetomidine infusion reduced isoflurane MAC by 43.4% versus 27.3% for lidocaine in 7 dogs — the combination reduced it by 60.9%

Experimental crossover MAC study (publication types: Journal Article, Research Support, Non-U.S. Gov't; the record's MeSH includes Random Allocation; the abstract does not state blinding)

Who: Dogs: 7 healthy adult dogs. Anaesthesia was induced with propofol and maintained with isoflurane. Baseline isoflurane MAC was determined after a 90-minute equilibration period; each dog then received, as a loading dose followed by a constant rate infusion, lidocaine 2 mg/kg then 100 µg/kg/minute, dexmedetomidine 2 µg/kg then 2 µg/kg/hour, or their combination, and MAC was determined again after 45 minutes of infusion.

Result: Compared with baseline MAC, lidocaine reduced isoflurane MAC by 27.3% (range 12.5-39.2%), dexmedetomidine by 43.4% (33.3-53.3%) and their combination by 60.9% (46.1-78.1%); all three reductions were significant, and the combination reduced MAC more than either drug alone. The authors conclude that, at the doses studied, both drugs provide a clinically important reduction in isoflurane concentration during anaesthesia in dogs.

Watch out: Only 7 dogs and a single dose pairing: the dexmedetomidine-versus-lidocaine gap (43.4% vs 27.3%) is dose-dependent, and MAC is a process measure in healthy experimental dogs, not a clinical outcome in surgical patients. The abstract does not report recovery times or recovery quality.

Acevedo-Arcique CM, Ibancovichi JA, Chavez JR, Gutierrez-Blanco E, Moran-Muñoz R, Victoria-Mora JM, Tendillo-Cortijo F, Santos-González M, Sanchez-Aparicio P. Lidocaine, dexmedetomidine and their combination reduce isoflurane minimum alveolar concentration in dogs. PLoS One. 2014;9(9):e106620. PMID: 25232737. Registry ID: none in the record. MeSH: Anesthesia, Inhalation* · Anesthetics, Combined/pharmacology · Anesthetics, Inhalation/pharmacology · Animals · Blood Gas Analysis · Dexmedetomidine/pharmacology* · Dogs · Drug Combinations · Female · Heart Rate/drug effects · Isoflurane/analysis* · Lidocaine/pharmacology* · Male · Pulmonary Alveoli/drug effects* · Random Allocation

Gutierrez-Blanco 2013: dexmedetomidine and lidocaine infusions spared nearly equal isoflurane during ovariohysterectomy — 24.8% versus 22.5% reduction in 54 dogs; fentanyl and the combination significantly reduced end-tidal isoflurane and spared more than lidocaine, ketamine or control, but not at all times — no superiority over dexmedetomidine is reported

Randomized, prospective, blinded, clinical study (record's own wording; publication types: Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't)

Who: Dogs: 54 dogs undergoing ovariohysterectomy. Anaesthesia was induced with propofol and maintained with isoflurane, with one of six intravenous treatments: butorphanol/saline control (CONTROL/BUT), fentanyl (5 µg/kg, then 10 µg/kg/hour), ketamine, lidocaine (2 mg/kg, then 100 µg/kg/minute, LIDO), dexmedetomidine (1 µg/kg, then 3 µg/kg/hour, DEX), or lidocaine-ketamine-dexmedetomidine (LKD). An anaesthetist unaware of treatment and of end-tidal isoflurane concentration adjusted the vaporiser to maintain surgical anaesthetic depth.

Result: Overall mean ± SD end-tidal isoflurane and percentage reduction in isoflurane requirement during surgery were: FENT 1.01 ± 0.31 / 41.6%, KET 1.37 ± 0.19 / 20.8%, LIDO 1.34 ± 0.19 / 22.5%, DEX 1.30 ± 0.28 / 24.8%, LKD 0.95 ± 0.19 / 54.9% and CONTROL/BUT 1.73 ± 0.18 / 0.0%. FENT and LKD significantly reduced end-tidal isoflurane; at the doses administered, FENT and LKD had a greater isoflurane-sparing effect than LIDO, KET or CONTROL/BUT, but not at all times. Heart rate was lower in FENT than in other groups except DEX and LKD, and mean arterial pressure was lower in FENT and CONTROL/BUT than in DEX.

Watch out: This is the only carded clinical (surgical-patient) trial, and in it the dexmedetomidine-versus-lidocaine difference is small (24.8% vs 22.5% reduction) and was not reported as a significant head-to-head contrast; the abstract reports no recovery outcome. Six arms in 54 dogs means about 9 dogs per arm. The same 54 dogs' postoperative analgesia results are reported separately (PMID: 25039918) — a pain question, cross-pointed in the synthesis, not carded here.

Gutierrez-Blanco E, Victoria-Mora JM, Ibancovichi-Camarillo JA, Sauri-Arceo CH, Bolio-González ME, Acevedo-Arcique CM, Marin-Cano G, Steagall PV. Evaluation of the isoflurane-sparing effects of fentanyl, lidocaine, ketamine, dexmedetomidine, or the combination lidocaine-ketamine-dexmedetomidine during ovariohysterectomy in dogs. Vet Anaesth Analg. 2013;40(6):599-609. PMID: 23910822. Registry ID: none in the record. MeSH: Anesthesia, General/methods, veterinary* · Anesthetics, Combined*/administration & dosage · Anesthetics, Inhalation*/administration & dosage · Anesthetics, Intravenous*/administration & dosage · Animals · Dexmedetomidine*/administration & dosage · Dogs/surgery* · Female · Fentanyl*/administration & dosage · Hysterectomy/veterinary* · Isoflurane/administration & dosage* · Ketamine*/administration & dosage · Lidocaine*/administration & dosage · Ovariectomy/veterinary*

El-Hawari 2022: dexmedetomidine spared 40.3% of sevoflurane MAC versus 12.7% for lidocaine in 6 Beagles — the tramadol-lidocaine-dexmedetomidine combination spared 67.4%

Experimental crossover MAC study (publication type: Journal Article; the abstract does not state randomisation or blinding)

Who: Dogs: 6 healthy Beagle dogs. Sevoflurane MAC was determined by the tail-clamp method on five separate occasions: no treatment (control), tramadol (1.5 mg/kg intravenously, then 1.3 mg/kg/hour), lidocaine (2 mg/kg intravenously, then 3 mg/kg/hour), dexmedetomidine (2 µg/kg intravenously, then 2 µg/kg/hour), and their combination. Cardiorespiratory variables were recorded every five minutes and immediately before each noxious stimulus.

Result: Sevoflurane MAC sparing was 5.1 ± 25.3% for tramadol, 12.7 ± 14.3% for lidocaine, 40.3 ± 15.1% for dexmedetomidine and 67.4 ± 13.9% for the combination, which had the greatest sparing effect. Cardiorespiratory variables remained within the clinically acceptable range on the combination, although mean arterial pressure was higher and accompanied by bradycardia; the authors caution that cardiorespiratory variables should be monitored carefully to avoid undesirable side effects induced by dexmedetomidine.

Watch out: Six Beagles only, and the lidocaine sparing estimate is imprecise (12.7 ± 14.3%, and the tramadol estimate's spread crosses zero). The inhalant is sevoflurane, not the isoflurane of the other two cards, and this is again a MAC process measure in healthy dogs, with no recovery outcome reported.

El-Hawari SF, Oyama N, Koyama Y, Tamura J, Itami T, Sano T, Yamashita K. Sparing effect of tramadol, lidocaine, dexmedetomidine and their combination on the minimum alveolar concentration of sevoflurane in dogs. J Vet Sci. 2022;23(4):e53. PMID: 35698808. Registry ID: none in the record. MeSH: Anesthetics, Inhalation*/pharmacology · Animals · Dexmedetomidine*/pharmacology · Dogs · Lidocaine/pharmacology · Methyl Ethers*/pharmacology · Pulmonary Alveoli · Sevoflurane/pharmacology · Tramadol*/pharmacology

Synthesis: both infusions spare inhalant; dexmedetomidine spared more in two small MAC studies but not in the one clinical trial, and recovery was not compared — POSSIBLE

Synthesis

Who: Synthesis of the three cards above: Acevedo-Arcique 2014 (7 dogs, isoflurane MAC crossover), Gutierrez-Blanco 2013 (54 dogs, ovariohysterectomy, randomised blinded clinical trial) and El-Hawari 2022 (6 Beagles, sevoflurane MAC crossover).

Result: (1) Inhalant sparing, dexmedetomidine vs lidocaine: 43.4% vs 27.3% reduction in isoflurane MAC (Acevedo-Arcique 2014); 40.3% vs 12.7% sparing of sevoflurane MAC (El-Hawari 2022); 24.8% vs 22.5% reduction in end-tidal isoflurane during surgery (Gutierrez-Blanco 2013). (2) Combinations spared more than either drug alone in all three studies (60.9%, 67.4% and 54.9% respectively), and fentanyl also spared more numerically than either single drug in the clinical trial (41.6% vs 24.8%/22.5%); a significant head-to-head difference vs dexmedetomidine is not reported. (3) Recovery: no carded record compares recovery between the two infusions. (4) Design class (a): randomisation and blinding are established by Gutierrez-Blanco 2013, a carded record answering this shelf's own comparison in this shelf's own population.

Watch out: One-home check at drafting: PMIDs 25232737, 23910822 and 35698808 do not appear in any other pack on disk. Records deliberately not carded as claim-carriers: Gutierrez-Blanco 2015 (PMID: 25039918) reports postoperative analgesia in the same 54 dogs — a pain outcome, not inhalant sparing or recovery; Ebner 2013 (PMID: 23802667) compares dexmedetomidine with morphine-lidocaine-ketamine and the four-drug combination (no lidocaine-alone arm), and found time to extubation and sternal recumbency did not differ among its treatments; the horse study of lidocaine alone versus lidocaine-dexmedetomidine (PMID: 41295727) is a different species and a different comparison. Boundary: dexmedetomidine versus acepromazine premedication is Shelf #317 and midazolam co-induction is Shelf #530 — different comparisons, desk-checked and not used here. All sparing figures are dose-specific: a different dose pairing could change or reverse the dexmedetomidine-versus-lidocaine gap.

Synthesis of Acevedo-Arcique CM et al. PMID: 25232737; Gutierrez-Blanco E et al. PMID: 23910822; El-Hawari SF et al. PMID: 35698808. Registry IDs as on the individual cards.

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