Physiologic and biochemical assessments of koi (Cyprinus carpio) following immersion in propofol

Objective—To determine efficacy of propofol as an immersion agent to induce general anesthesia in koi (Cyprinus carpio). Design—Prospective, crossover study. Animals—10 adult koi (mean ± SD weight, 325 ± 81 g). Procedures—Koi were exposed to each of 4 concentrations of propofol (1, 2.5, 5, and 10 mg/L) with a 1-week washout period between trials. In a subsequent trial, koi were anesthetized with propofol (5 mg/L) and anesthesia was maintained with propofol (3 mg/L) for 20 minutes. Response to a noxious stimulus was assessed by means of needle insertion into an epaxial muscle. Results—At a propofol concentration of 1 mg/L, koi were sedated but never anesthetized. At propofol concentrations of 2.5, 5, and 10 mg/L, mean ± SD anesthetic induction times were 13.4 ± 3.3, 3.8 ± 1.1, and 2.3 ± 0.9 minutes, respectively; mean recovery times were 12.9 ± 8.3, 11.0 ± 6.3, and 18.1 ± 13.0 minutes; mean heart rates were 57 ± 25, 30 ± 14, and 22 ± 14 beats/min; mean opercular rates were 58 ± 18, 68 ± 15, and 48 ± 22 beats/min; and 1 of 10, 2 of 10, and 0 of 10 fish responded to needle insertion. All fish recovered satisfactorily. Following 20 minutes of anesthesia, 2 fish had recovery times > 4 hours and 1 fish died. Conclusions and Clinical Relevance—Immersion in propofol at concentrations ≥ 2.5 mg/L induced general anesthesia in koi. Maintenance of anesthesia with propofol for 20 minutes was associated with prolonged recovery times in 2 of 9 and death in 1 of 9 koi.