To investigate the cytotoxic effects of 2 different concentrations of buprenorphine and compare them with bupivacaine and morphine on healthy equine chondrocytes in vitro.
Primary cultured equine articular chondrocytes from 3 healthy adult horses.
Chondrocytes were exposed for 0 and 2 hours to the following treatments: media (CON; negative control); bupivacaine at 2.2 mg/mL (BUPI; positive control); morphine at 2.85 mg/mL (MOR); buprenorphine at 0.12 mg/mL (HBUPRE); or buprenorphine at 0.05 mg/mL (LBUPRE). Chondrocyte viability was assessed using live/dead staining, water-soluble tetrazolium salt-8 (WST-8) cytotoxic assay, LDH assay, and flow cytometry. All continuous variables were evaluated with a mixed ANOVA with treatment, time, and their interactions as the fixed effects and each horse as the random effect.
Buprenorphine showed a concentration-dependent chondrotoxic effect. The viability of chondrocytes was significantly decreased with exposure to HBUPRE and BUPI compared to CON, MOR, and LBUPRE.
Negligible chondrotoxic effects were observed in healthy cultured equine chondrocytes exposed to 0.05 mg/mL of buprenorphine, whereas higher concentrations (0.12 mg/mL) showed a marked cytotoxic effect. Based on these results, low concentrations of buprenorphine appear to be safe for intra-articular administration. Further evaluation of this dose in vivo is needed before recommending its clinical use.
To determine the dose of alfaxalone for IM administration combined with dexmedetomidine and hydromorphone that would allow endoscopic-guided orotracheal intubation in rabbits without causing a decrease in respiratory rate or apnea.
15 sexually intact (9 females and 6 males) healthy Miniature Lop rabbits weighing a mean ± SD of 2.3 ± 0.3 kg and ranging in age from 4 to 9 months.
In a randomized, controlled clinical trial, rabbits received 0.1 mg of hydro-morphone/kg and 0.005 mg of dexmedetomidine/kg, plus alfaxalone at either 2 mg/kg (5 rabbits), 5 mg/kg (5 rabbits), or 7 mg/kg (5 rabbits). Drugs were mixed in a single syringe and administered IM. Semiquantitative rating scales were used to evaluate quality of anesthesia and intubation. Orotracheal intubation was attempted with endoscopy and confirmed by capnography.
The number of successful intubations was 0, 3, and 4 in rabbits receiving 2, 5, and 7 mg of alfaxalone/kg, respectively. Median (range) anesthesia quality scores (scale, 0 to 12; 12 = deepest anesthesia) were 3 (2 to 5), 6 (5 to 6), and 6 (4 to 9) for rabbits receiving 2, 5, and 7 mg of alfaxalone/kg, respectively. The median (range) intubation quality scores (scale, 0 to 3 [ie, intubation not possible to easiest intubation]) were 0 (0 to 0), 2 (0 to 3), and 2 (0 to 3) for rabbits receiving 2, 5, and 7 mg of alfaxalone/kg, respectively. None of the rabbits experienced a decrease in respiratory rate or apnea.
CONCLUSIONS AND CLINICAL RELEVANCE
Increasing doses of alfaxalone combined with hydromorphone and dexmedetomidine increased the success rate of endoscopic-guided orotracheal intubation. Increasing the dose of alfaxalone had no effect on respiratory rate.
To investigate the effects of a priming dose of alfaxalone on the total anesthetic induction dose for and cardiorespiratory function of sedated healthy cats.
8 healthy adult cats.
For this crossover study, cats were sedated with dexmedetomidine and methadone administered IM. Cats next received a priming induction dose of alfaxalone (0.25 mg/kg, IV) or saline (0.9% NaCl) solution (0.025 mL/kg, IV) over 60 seconds and then an induction dose of alfaxalone (0.5 mg/kg/min, IV) until orotracheal intubation was achieved. Cardiorespiratory variables were recorded at baseline (immediately prior to priming agent administration), immediately after priming agent administration, after orotracheal intubation, and every 2 minutes until extubation. The total induction dose of alfaxalone was compared between the 2 priming agents.
Mean ± SD total anesthetic induction dose of alfaxalone was significantly lower when cats received a priming dose of alfaxalone (0.98 ± 0.28 mg/kg), compared with when cats received a priming dose of saline solution (1.41 ± 0.17 mg/kg). Mean arterial blood pressure was significantly higher when alfaxalone was used as the priming dose. No cats became apneic or had a hemoglobin oxygen saturation of < 90%. Expired volume per minute was not significantly different between the 2 priming agents.
CONCLUSIONS AND CLINICAL RELEVANCE
Administration of a priming dose of alfaxalone to healthy sedated cats reduced the total dose of alfaxalone needed to achieve orotracheal intubation, maintained mean arterial blood pressure, and did not adversely impact the measured respiratory variables.