Antinociceptive Effect of a Sacro-Coccygeal Epidural of Morphine and Lidocaine in Cats Undergoing Ovariohysterectomy.

BACKGROUND: A commonly described analgesic protocol for ovariohysterectomy (OHE) combines systemic opioids, sedatives, and non-steroidal anti-inflammatory drugs. However, systemic analgesia does not fully prevent perioperative visceral and somatic pain triggered by the surgical stimulus. OBJECTIVES: To compare the analgesic effects and quality of recovery of systemic analgesia with those of a sacrococcygeal epidural injection of lidocaine and morphine in cats undergoing elective OHE. Methods: Twenty domestic female cats were premedicated with dexmedetomidine (0.01 mg kg-1 IM) and alfaxalone (1.5 mg kg-1 IM) and randomly assigned to one of two analgesic protocols: methadone (0.2 mg kg-1 IM) in the control group CTR (n = 10) and methadone (0.1 mg kg-1 IM) + epidural (lidocaine 2% (0.3 mL kg-1) + morphine 1% (0.1 mg kg-1) diluted with NaCl 0.9% to a total volume of 1.5 mL in the SCC-E group (n = 10). General anaesthesia was induced with alfaxalone (1 mg kg-1 IV) and maintained with sevoflurane in 100% oxygen. Non-invasive blood arterial pressure and cardiorespiratory variables were recorded. The quality of recovery was assessed using a simple descriptive scale. Before surgery and 1, 2, 3, 4, 6, and 8 h post-op pain was assessed using the UNESP-Botucatu multidimensional composite pain scale (MCPS) and mechanical nociception thresholds (MNT). The repeated measures analysis of variance (ANOVA) was used to compare groups over time. Comparison between groups was performed using independent samples t-test if the assumption of normality was verified, or the Mann-Whitney test. The chi-square test of independence and exact Fisher's test were used to compare groups according to recovery quality. RESULTS: Heart rate and systolic arterial pressure increased significantly from baseline values in the CTR group and did not change in the SCC-E group. In the CTR group, MNT and UNESP-Botucatu-MCPS scores increased significantly from baseline for all assessment points and the first 3 h, respectively, whereas this did not occur in the SCC-E group. CONCLUSIONS AND CLINICAL RELEVANCE: Based on our results, the SCC-E administration of lidocaine 2% with morphine 1% is a reasonable option to provide perioperative analgesia in cats submitted to OHE, compared to a systemic protocol alone.

Description of a new approach for great auricular and auriculotemporal nerve blocks: A cadaveric study in foxes and dogs.

Otitis externa is a painful condition that may require surgical intervention in dogs. A balanced analgesia protocol should combine systemic analgesic agents and local anaesthesia techniques. The aim of the study was to find anatomical landmarks for the great auricular and the auriculotemporal nerves that transmit nociceptive information from the ear pinna and to develop the optimal technique for a nerve block. The study consisted of two phases. In phase I, one fox cadaver was used for dissection and anatomical localization of the auricular nerves to derive landmarks for needle insertion. Eight fox cadavers were subsequently used to evaluate the accuracy of the technique by injecting methylene blue bilaterally. In phase II findings from phase I were applied in four Beagle canine cadavers. A block was deemed successful if more than 0.6 cm of the nerve's length was stained. Successful great auricular nerve block was achieved by inserting the needle superficially along the wing of the atlas with the needle pointing towards the jugular groove. For the auriculotemporal nerve block the needle was inserted perpendicular to the skin at the caudal lateral border of the zygomatic arch, close to the temporal process. The overall success rate was 24 out of 24 (100%) and 22 out of 24 (91%) for the great auricular and the auriculotemporal nerves, respectively, while the facial nerve was stained on three occasions. Our results suggest that it is feasible to achieve a block of the auricular nerves, based on anatomical landmarks, without concurrently affecting the facial nerve.

Effects of different doses of dexmedetomidine on anaesthetic induction with alfaxalone--a clinical trial.

OBJECTIVE: To document the effects of two doses of dexmedetomidine on the induction characteristics and dose requirements of alfaxalone. STUDY DESIGN: Randomized controlled clinical trial. ANIMALS: Sixty one client owned dogs, status ASA I-II. METHODS: Dogs were allocated randomly into three groups, receiving as pre-anaesthetic medication, no dexmedetomidine (D0), 1 µg kg(-1) dexmedetomidine (D1 ) intramuscularly (IM) or 3 µg kg(-1) dexmedetomidine IM (D3). All dogs also received 0.2 mg kg(-1) methadone IM. Level of sedation was assessed prior to induction of anaesthesia. Induction of general anaesthesia was performed with alfaxalone administered intravenously to effect at a rate of 1 mg kg(-1) minute(-1) ; the required dose to achieve tracheal intubation was recorded. Anaesthesia was maintained with isoflurane in oxygen. Cardiopulmonary parameters were recorded throughout the anaesthetic period. Quality of intubation, induction and recovery of anaesthesia were recorded. Quantitative data were compared with one-way anova or Kruskal-Wallis test. Repeated measures were log-transformed and analysed with repeated measures anova (p < 0.05). RESULTS: Treatment groups were similar for categorical data, with exception of sedation level (p < 0.001). The doses (mean ± SD) of alfaxalone required for intubation were D0 1.68 ± 0.24, D1 1.60 ± 0.36 and D3 1.41 ± 0.43, the difference between D0 and D3 being statistically significant (p = 0.036). Heart and respiratory rates during the anaesthetic period were significantly different over time and between groups (p < 0.001); systolic arterial blood pressure was significantly different over time (p < 0.001) but not between groups (p = 0.833). Induction quality and recovery scores were similar between groups (p = 1.000 and p = 0.414, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: The administration of alfaxalone resulted in a good quality anaesthetic induction which was not affected by the dose of dexmedetomidine. Dexmedetomidine at 3 µg kg(-1) IM combined with methadone provides good sedation and enables a reduction of alfaxalone requirements.

Comparison of quality of recovery from anaesthesia in cats induced with propofol or alfaxalone.

OBJECTIVE: To assess the quality and length of recovery from anaesthesia induced with either propofol or alfaxalone and maintained with isoflurane, in cats undergoing short procedures in private veterinary practice. STUDY DESIGN: Prospective, blinded, randomized study. ANIMALS: Ninety-three healthy mixed breed cats. METHODS: After premedication with intramuscular acepromazine (0.05 mg kg(-1)) and buprenorphine (0.01 mg kg(-1)), cats were randomly allocated to receive either propofol (Group P) or alfaxalone (Group A) for induction of anaesthesia. Following endotracheal intubation, anaesthesia was maintained with isoflurane vaporized in oxygen. The quality of induction, physiological parameters throughout anaesthesia and the duration of both surgery and anaesthesia were recorded. The level of ambient noise, recovery times, number of attempts to stand, reaction of the cat to touch 15 minutes after extubation, and other relevant characteristics of the recovery period were noted and a video recording of the recovery was made. The videos were assessed by a second, blinded anaesthetist, using simple descriptive and visual analogue scales. RESULTS: No statistically significant differences between groups with respect to preoperative data, premedication, surgery, anaesthesia and recovery times and scores were observed. There was a statistically significant difference in the number of patients paddling and trembling on recovery in Group A (p = 0.032) even though there was no statistically significant difference in the level of ambient noise in the recovery ward or in the overall quality of recovery. CONCLUSIONS: Both propofol and alfaxalone provide good recovery characteristics in premedicated cats undergoing short procedures in clinical settings. Alfaxalone induction was associated with more episodes of paddling and trembling during recovery. CLINICAL RELEVANCE: Both agents would appear appropriate for induction of anaesthesia in cats for short procedures.