Physiologic and antinociceptive effects following intramuscular administration of xylazine hydrochloride in combination with tiletamine-zolazepam in llamas

摘要

Objective-To evaluate antinociceptive and selected effects associated with IM administration of xylazine hydrochloride in combination with tiletamine-zolazepam in llamas. Animals-8 adult male llamas. Procedures-Each llama received tiletamine-zolazepam (2 mg/kg) combined with either xylazine (0.1, 0.2, or 0.4 mg/kg) or saline (0.9% NaCl) solution IM (treatments designated as TZ-Xy0.1,TZ-Xy0.2,TZ-Xy0.4, and TZ-Sal, respectively) at 1-week intervals. Selected cardiorespiratory variables were assessed during lateral recumbency and anesthesia, and recovery characteristics were recorded. Duration of antinociception was evaluated by clamping a claw every 5 minutes. Results-Interval between treatment administration and lateral recumbency for TZ-Xy0.4 was shorter than that for TZ-Xy0.1 or TZ-Sal. Mean +/- SEM duration of antinociception was longer for TZ-Xy0.4 (51.3 +/- 70 minutes), compared with findings for TZ-Xy0.2 (31.9 +/- 6.0 minutes), TZ-Xy0.1 (8.1 +/- 4.0 minutes), and TZ-Sal (0.6 +/- 0.6 minutes). Interval between treatment administration and standing was longer for TZ-Xy0.4 (112 +/- 9 minutes) than it was for TZ-Xy0.2 (77 +/- 9 minutes) or TZ-Sal (68 +/- 9 minutes). Mean heart and respiratory rates during the first 30 minutes for TZ-Sal exceeded values for the other treatments. Administration of TZ-Xy0.2 and TZ-Xy0.4 resulted in Pao(2) < 60 mm Hg at 5 minutes after llamas attained lateral recumbency, and values differed from TZ-Sal findings at 5, 10, and 15 minutes; Paco(2) was greater for TZ-Xy(0.2) and TZ-Xy(0.4) than for TZ-Sal at 5, 10, 15, and 20 minutes. Conclusions and Clinical Relevance-Xylazine (0.2 and 0.4 mg/kg) increased the duration of antinociception in llamas anesthetized with tiletamine-zolazepam. (Am J Vet Res 2013;74:530-534)