Cardiopulmonary effects of anaesthesia maintained by propofol infusion versus isoflurane inhalation in cheetahs (Acinonyx jubatus)

Abstract

Objective: To compare the cardiopulmonary effects of propofol total intravenous anaesthesia (TIVA) with isoflurane in cheetahs (Acinonyx jubatus) to evaluate feasibility for field use.

Study design: Prospective clinical study.

Animals: A group of 24 adult cheetahs, 12 per group.

Methods: Cheetahs were immobilized with zolazepam/tiletamine (1.2 mg kg^-1) and medetomidine [40 μg kg^-1, both intramuscular (IM)] by darting. A maintenance protocol of propofol TIVA (group P) or isoflurane inhalation (group I) was assigned randomly to each cheetah. Anaesthesia was maintained for at least 60 minutes. Cheetahs breathed spontaneously throughout; oxygen was supplemented at 3 L minute^-1. Cardiopulmonary parameters were recorded at 5 minute intervals and three arterial blood gas samples were analysed. Following maintenance, atipamezole was administered IM (200 μg kg^-1) and recovery was observed. Data are reported as mean±standard deviation; variables over time were compared using a linear mixed model (fixed: time, treatment; random: cheetah).

Results: Lack of response to manipulations was maintained in all cases (end-tidal isoflurane percentage 1.1±0.1%, propofol rate maintained at 0.1 mg kg^-1 minute^-1). The heart and respiratory rates were acceptable throughout maintenance. The end-tidal carbon dioxide tension increased slowly [44.0±5.0 mmHg (5.87±0.67 kPa)] with no differences between groups. All cheetahs were initially markedly hypertensive [mean arterial blood pressure (MAP): (163±17 mmHg)]. The MAP normalized for group I (125±30 mmHg) but remained high for group P (161±17 mmHg) (p < 0.001). Arterial carbon dioxide tension [48.9±14.6 mmHg (6.52±1.95 kPa)] never differed between groups. Initial arterial oxygen tension indicated borderline hypoxaemia, but improved with oxygen supplementation. Recovery time was 10.8±5.0 and 51.9±23.5 minutes for group I and group P, respectively.

Conclusions and clinical relevance: Both protocols provided acceptable cardiopulmonary values. Propofol may be an alternative to isoflurane for field use, but the prolonged recovery may make it less suitable for long-term anaesthesia.

Keywords: Acinonyx jubatus; cheetah; isoflurane; propofol; total intravenous anaesthesia.