Hematological effects of etomidate and tricaine in common carp

Abstract

Hematological effects of etomidate and tricaine at concentrations causing general anesthesia or sedation of carp juveniles werecompared. Recovery of body balance took similar time in the case of both anesthetics, but fish treated with etomidate were depressedfor several hours, while those subjected to tricaine immediately regained normal behavior. Immediately after exposure anestheticscaused minor hematological changes; the only statistically significant effects (decrease of hematocrit and plasma glucose) occurredafter sedation with etomidate. One week after exposure a significant increase in mean corpuscular hemoglobin and mean corpuscularhemoglobin concentration occurred in all groups of fish compared to the previous values, with slight increase in hemoglobin anddecrease in red blood cell count. The mean corpuscular volume values tended to increase in all groups except for the control. Oxidativemetabolic activity of phagocytes was significantly higher in both groups treated with etomidate compared to the control and tricainegroups. The results revealed that etomidate was less aversive and better prevented a delayed immunosuppressive effect of stress causedby handling and bleeding, while very quick complete recovery was the benefit of tricaine. These findings suggest that etomidate is betterwhen long-term stress prevention is required, while tricaine is more useful for short-term immobilization of fish when rapid recoveryof normal behavior is needed.