Search

In this prospective, randomised, blinded clinical study, we compared the sedative, antinociceptive and cardiorespiratory effects of intranasal (IN) dexmedetomidine at 5 μg/kg (diluted with 0.03 mL/kg NaCl 0.9%, DEX) with or without methadone (0.3 mg/kg; DEXMET), through a mucosal atomization device to one nostril in twenty healthy client-owned dogs. At 5-min intervals over 45 min, sedation score, onset, cardiopulmonary variables, mechanical nociceptive thresholds (MNTs) were assessed, also ease of administration, adverse effects, and response to IV catheterization. Statistical analysis employed t-test, the Mann-Whitney U, repeated measures ANOVA and Chi-square tests as appropriate (P < 0.05). Higher sedation ocurred in DEXMET (7 [5–10]) compared to DEX (5 [2–7]) from 15 to 30 min (P < 0.01, median [interquartile range]). Heart rate was lower in DEXMET (P < 0.01; 65% reduction vs. 41% in DEX, P = 0.001). The MNTs were higher in DEXMET than DEX from 15 to 45 min (P < 0.01), peaking at T30 (17.1 ± 3.8, DEXMET and 8.5 ± 5.4 N, DEX). No differences were observed in mean arterial blood pressure and respiratory rate. Intranasal administration was considered easy for 8 dogs per group. Reverse sneezing (8 dogs; P < 0.001), sialorrhea and retching (4 and 2 dogs, respectively) occurred in DEXMET. Response to catheterisation was lower in DEXMET than DEX (P = 0.039; 2 and 7 dogs, respectively). In conclusion, intranasal methadone (0.3 mg/kg) increased the sedative and antinociceptive effects produced by dexmedetomidine (5 μg/kg) in healthy dogs and resulted in lower heart rate. • Methadone potentiated sedative effect of intranasal (IN) dexmedetomidine. • Methadone IN produced greater antinociceptive effects than dexmedetomidine alone. • Lower heart rate was observed when both drugs were administered IN. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the effects on mean arterial pressure (MAP) and ventilation of propofol total IV anaesthesia (TIVA) and isoflurane as anaesthetic maintenance in healthy dogs undergoing orthopaedic surgery, with epidural anaesthesia. Dogs were premedicated IM with dexmedetomidine (4 μg/kg) and methadone (0.3 mg/kg), induced with IV propofol (0.65–5 mg/kg) and randomly assigned to be maintained with isoflurane (group I) or propofol (group P). Isoflurane end-tidal concentration (EtISO) and propofol infusion rate were adjusted during the surgery to maintain a suitable anaesthetic depth. All dogs received bupivacaine (1 mg/kg) and morphine (0.1 mg/kg) in the lumbosacral epidural space (total volume 0.2 mL/kg). MAP was recorded every 5 min during the procedure. Statistical analysis was performed using parametric (Student’s t test) and nonparametric (Mann–Whitney U -test, chi-square) tests, as appropriate. Anaesthetic maintenance in groups I and P was accomplished by providing a mean EtISO of 1.12 ± 0.15% and a mean propofol infusion rate of 15.0 ± 4.7 mg/kg/h, respectively. MAP was significantly higher in group P than in group I (92 ± 17 mmHg versus 78 ± 10 mmHg; P = 0.021). Eleven dogs in group P and two dogs in group I reached an EtCO 2 > 7.3 kPa, requiring mechanical ventilation ( P = 0.001). In combination with epidural anaesthesia, propofol TIVA improved MAP and is a suitable alternative to isoflurane in orthopaedic surgery of the hind limb in healthy dogs. Nevertheless, since it was associated with increased respiratory depression, mechanical ventilation should be available. [ABSTRACT FROM AUTHOR]

The objectives of this study were to determine: (1) the sedative effects of dexmedetomidine in combination with methadone, midazolam, or both, and (2) the propofol dose required to achieve endotracheal intubation in healthy dogs. Seven healthy Beagle dogs were included in a prospective experimental, crossover, randomised and masked design. All dogs received four treatments IM, with at least 1 week between sessions, as follows: dexmedetomidine 5 µg/kg (D) alone, or combined with methadone 0.3 mg/kg (DMe), midazolam 0.3 mg/kg (DMi), or both (DMeMi). The degree of sedation was evaluated using a numerical scale (maximum 15 points). The dose of propofol required for intubation was also calculated for each group. Recovery time and quality were determined. Statistical analysis was performed using parametric (ANOVA) and nonparametric tests (Friedman, Cochran Q), as appropriate. The degree of sedation obtained with DMe and DMeMi (13, [7–14]; 13, [6–14], respectively) was significantly higher than in the control group (2, [1–4]; P  = 0.023, P  = 0.006, respectively). The required dose of propofol was lower in all groups (DMi, 1.5 ± 0.5 mg/kg, P  = 0.002; DMe, 1.2 ± 0.5 mg/kg, P  <   0.001; DMeMi, 0.9 ± 0.3 mg/kg) than in the control group (2.9 ± 0.9 mg/kg; P  <   0.001). Recovery quality was not different between groups ( P  = 0.137). In healthy dogs, the addition of midazolam did not enhance the sedative effects of dexmedetomidine or a dexmedetomidine–methadone combination at the doses studied, and propofol requirements were reduced. The sedative effect of dexmedetomidine was enhanced with methadone, and the required dose of propofol was reduced. [ABSTRACT FROM AUTHOR]