Cardiorespiratory and anaesthetic effects of two continuous rate infusions of dexmedetomidine in alfaxalone anaesthetized dogs.

Six Beagles were used in this prospective randomised crossover experimental study. Dexmedetomidine was administered at 0, 1 or 2 µg/kg IV for group C, LDA and HDA, respectively. Animals were induced and maintained with alfaxalone at 0.07 mg/kg/min with a CRI dexmedetomidine dose of 0, 0.5 or 1 µg/kg/h for group C, LDA and HDA, respectively. Cardiorespiratory variables, arterial blood gases and depth of anaesthesia were recorded. The recovery times and quality of recovery were scored. Group HDA produced a greater increase in the depth of anaesthesia than LDA. However, with both protocols, CI was halved compared to normal values in dogs. The use of oxygen before and during the anaesthetic maintenance is advisable, mainly if dexmedetomidine is going to be use as a pre-medicant and maintenance agent. The quality of recovery was better in groups receiving dexmedetomidine, without causing an increase in recovery time.

Cardiorespiratory, anaesthetic and recovery effects of morphine combined with medetomidine and alfaxalone in rabbits.

Ten New Zealand White rabbits were used in a crossover experimental study: 200 µg/kg medetomidine and 1 (M1) or 2 mg/kg (M2) morphine were administered intramuscularly. After preoxygenation, anaesthesia was induced with alfaxalone at 10 mg/kg intravenously. The trachea was intubated and 60 per cent oxygen provided. Heart and respiratory rates (HR and RR), direct arterial pressures (APs), arterial pH (pHa), PaO2, PaCO2 and SaO2 were taken at baseline, after premedication and every 10 minutes during the 90 minutes following induction. The times to return the ear pinch, toe pinch and righting reflexes were recorded. Data were analysed using a two-way analysis of variance and a paired samples t test. Compared to baseline values, HR, RR, APs, PaO2 and SaO2 decreased significantly after premedication in both groups. Postinduction apnoea of 20 ± 10 with M1 and 27 ± 18 minutes with M2 was experienced following alfaxalone administration, intermitent positive pressure ventilation was applied until spontaneous breathing efforts appeared. Cardiovascular variables, RR and pHa remained below, and PaCO2 over baseline values during the anaesthetic period. No significant differences were observed in the recovery times. Morphine at 1 or 2 mg/kg combined with medetomidine and alfaxalone in rabbits produced a suitable level of anaesthesia, although profound cardiorespiratory depression was found.

Postoperative analgesic effects of dexketoprofen, buprenorphine and tramadol in dogs undergoing ovariohysterectomy.

The objective of this study was to compare the postoperative analgesic effects of dexketoprofen, tramadol, and buprenorphine in dogs undergoing ovariohysterectomy. Seventy-five adult female dogs were randomly assigned to receive an intravenous injection (IV) of 1mg/kg of dexketoprofen (D), 0.02 mg/kg of buprenorphine (B) or 2mg/kg of tramadol (T). Pain assessment was performed during 48 h after ovariohysterectomy using a dynamic interactive visual analogue scale (DIVAS) and Glasgow composite measure pain scale (CMPS-SF). Rescue analgesia was required in 43%, 21%, and 5% of dogs in the B, T, and D groups, respectively, with significant differences between B and D (p=0.010) groups. The DIVAS and CMPS-SF values of the B group were significantly higher than those of the T and D groups. The most common undesirable effect was dysphoria in dexketoprofen group. Tramadol and dexketoprofen provide superior postoperative analgesia compared with buprenorphine in dogs undergoing ovariohysterectomy.

Anaesthetic and cardiorespiratory effects of a constant-rate infusion of alfaxalone in desflurane-anaesthetised sheep.

A prospective, randomised, blinded controlled study was performed to determine the anaesthetic and cardiorespiratory effects of a constant-rate infusion (CRI) of alfaxalone in 12 sheep anaesthetised with desflurane, and undergoing experimental orthopaedic surgery. Sheep were sedated with dexmedetomidine (4 µg/kg, intravenously) and butorphanol (0.3 mg/kg, intravenously). Anaesthesia was induced with alfaxalone (1 mg/kg/minute to effect, intravenously) and maintained with desflurane in oxygen and alfaxalone 0.07 mg/kg/minute or saline for 150 minutes (range 150-166 minutes). The anaesthetic induction dose of alfaxalone, the desflurane expiratory fraction required for anaesthetic maintenance, cardiorespiratory measurements and blood-gases were recorded at predetermined intervals. Quality of sedation, anaesthetic induction and recovery were assessed. The alfaxalone induction dose was 1.7 mg/kg (1.2 to 2.6 mg/kg). The desflurane expiratory fraction was lower (22 per cent) in sheep receiving alfaxalone CRI (P=0). Also, heart rate (P=0), cardiac index (P=0.002), stroke index (P=0) and contractility (P=0) were higher, and systemic vascular resistance (P=0.002) was lower. Although respiratory rate tended to be higher with alfaxalone, there was no difference in PCO2 between the groups. Recovery times were significantly longer in sheep given alfaxalone (25.4 v 9.5 minutes) but recovery quality was similar. Alfaxalone reduced requirements of desflurane and maintained similar cardiorespiratory function, but recovery time was more prolonged.