Hematological Response of Juvenile Cobia to Three Anesthetics

Abstract

Optimal concentrations of three anesthetics for use with juvenile cobia (Rachycentron canadum) were determined using time-to-recovery and hematological datasets. Buffered MS-222, clove oil and 2-phenoxyethanol (2-PE) were examined. Juvenile cobia were exposed to three concentrations of each anesthetic at 24 °C. Based on time to recovery, optimal doses for MS-222 was determined as 120-mg L−1, that for 2-PE, 0.4-mL L−1 and, for clove oil, 5-mL L−1. The hematological response of cobia to anesthesia included quantification of whole blood pH, pCO2, pO2, and Ca2+, K+, Na+, Cl−, hematocrit and glucose. Irrespective of anesthetic employed, cobia expressed metabolic acidosis, with changes in blood pH (p < 0.001) being matched by increases (p < 0.001) in pCO2. Anesthesia tended to increase blood Na+, hematocrit, pO2, Ca2+, and K+ although differential responses between anesthetics were recorded, suggesting different modes of action. A combination of recovery and hematological data indicated that when anesthesia is necessary, MS-222 represents the sedative of choice.