Sedative and antinociceptive effects of different combinations of detomidine and methadone in standing horses

Author(s)

Gozalo-Marcilla, Miguel ^[1] ; Luna, Stelio P. L. ^[1] ; Crosignani, Nadia ^[1] ; Puoli Filho, Jose N. P. ^[2] ; Possebon, Fabio S. ^[3] ; Pelligand, Ludovic ^{[4, 5, 6]} ; Taylor, Polly M. ^[7]

Affiliation

^[1] Sao Paulo State Univ UNESP, Sch Vet Med & Anim Sci, Dept Vet Surg & Anaesthesiol, Botucatu, SP - Brazil

^[2] Sao Paulo State Univ UNESP, Sch Vet Med & Anim Sci, Dept Anim Prod, Botucatu, SP - Brazil

^[3] Sao Paulo State Univ UNESP, Sch Vet Med & Anim Sci, Dept Vet Hyg & Publ Hlth, Botucatu, SP - Brazil

^[4] Royal Vet Coll, Dept Comparat Biomed Sci, Hatfield, Herts - England

^[5] Royal Vet Coll, Dept Clin Serv, Hatfield, Herts - England

^[6] Royal Vet Coll, Dept Sci, Hatfield, Herts - England

^[7] Taylor Monroe, Ely - England

• Document type: Journal article
• Source: VETERINARY ANAESTHESIA AND ANALGESIA; v. 44, n. 5, p. 1116-1127, SEP 2017.
• Web of Science Citations: 7

Abstract

Objective To evaluate intravenous (IV) detomidine with methadone in horses to identify a combination which provides sedation and antinociception without adverse effects. Study design Randomized, placebo-controlled, blinded, crossover. Animals A group of eight adult healthy horses aged (mean +/- standard deviation) 7 +/- 2 years and 372 +/- 27 kg. Methods A total of six treatments were administered IV: saline (SAL); detomidine (5 mu g kg(-1); DET); methadone (0.2 mg kg(-1); MET) alone or combined with detomidine {[}2.5 (MLD), 5 (MMD) or 10 (MHD) mu g kg(-1)]. Thermal, mechanical and electrical nociceptive thresholds were measured, and sedation, head height above ground (HHAG), cardiopulmonary variables and intestinal motility were evaluated at 5, 15, 30, 45, 60, 75, 90, 120 and 180 minutes. Normal data were analyzed by mixed-model analysis of variance and non-normal by Kruskal-Wallis (p < 0.05). Results Nociceptive thresholds in horses administered methadone with the higher doses of detomidine (MMD, MHD) were increased above baseline to a greater degree and for longer duration (MMD: 15-30 minutes, MHD: 30-60 minutes) than in horses administered low dose with methadone or detomidine alone (MLD, DET: 5-15 minutes). No increases in nociceptive thresholds were recorded in SAL or MET. Compared with baseline, HHAG was lower for 30 minutes in MMD and DET, and for 45 minutes in MHD. No significant sedation was observed in SAL, MET or MLD. Intestinal motility was reduced for 75 minutes in MHD and for 30 minutes in all other treatments. Conclusions Methadone (0.2 mg kg(-1)) potentiated the antinociception produced by detomidine (5 mu g kg(-1)), with minimal sedative effects. Clinical relevance Detomidine (5 mu g kg(-1)) with methadone (0.2 mg kg(-1)) produced antinociception without the adverse effects of higher doses of detomidine. (AU)

• FAPESP's process: 10/08967-0 - Evaluation of clinical and experimental pain in animals
• Grantee: Stelio Pacca Loureiro Luna
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 14/00474-5 - Antinociceptive effects and farmacokinetics in horses treated with different low doses of methadone and detomidine
• Grantee: Miguel Gozalo Marcilla
• Support Opportunities: Scholarships in Brazil - Post-Doctoral