Midazolam/butorphanol/ketamine and the clinically effective dose of isoflurane anesthesia of ostriches (Struthio camelus)

Ostrich production facilities expanded exponentially in the United States, leading to crowded conditions and new disease states that required close examination and, occasionally, surgical intervention. Manual restraint was usually inadequate and often dangerous to both the ostrich and the handler, and necessitated chemical immobilization. Few repeatable anesthetic techniques have been established for ostriches. This report describes a predictable general anesthetic technique for ostriches. Seven adult, domesticated ostriches (three male; four female), estimated to weigh 99.2 ± 6.2 kg (mean ± SEM) were hand injected with 0.2 mg kg−1 midazolam and 0.4 mg kg−1 butorphanol IM in the mid-dorsum. Sedative effects were evident and anesthesia was induced 34.13 ± 1.88 minutes after sedation with ketamine (8.69 ± 0.51 mg kg−1 IV in the right jugular vein), followed by intubation and isoflurane anesthesia under controlled ventilation (PaCO2 35–45 mm Hg, 4.7–6 kPa) for surgery (proventriculotomy, n = 6; neck laceration, n = 1). The laceration subject required a second anesthesia one month later. Temperature, ECG, pulse oximetry, blood gases, exhaled gases and arterial blood pressures were monitored and supported. To assess inhalant anesthetic requirement a simple step-down, step-up method (10–20% change) was applied, maintaining a given end-tidal isoflurane (ETISO) concentration for a minimum of 15 minutes during surgical stimulation and observing gross purposeful head movement. Movement was noted at ETiso 1.69 ± 0.11% at the first step-down approach (n = 8), 1.66 ± 0.09% (n = 5) at the second and 1.78 ± 0.06 (n = 4) at the third. Body temperature at instrumentation was 37.2 ± 0.3 °C and dropped to 35.8 ± 0.5 °C by the end of the procedure. Time from induction to start of the step-down analysis was 80.9 ± 20.0 minutes with a total anesthesia time of 268.3 ± 37.4 minutes. In recovery ETISO for head movement was 0.48 ± 0.06%. This movement was followed immediately by 5 mg butorphanol IV, and provided 14.4 ± 2.3 minutes before the next head movement. The second movement was followed immediately by naloxone (0.01 mg kg−1 IV) and minimal delirium in recovery. A relatively controlled, repeatable method for anesthesia of domesticated ostriches was established.