Biochemical, Histopathologic, Physiologic, and Behavioral Effects of Nonsteroidal Antiinflammatory Drugs in Rainbow Trout (Oncorhynchus mykiss).

Because the number of fish being used in research is increasing rapidly, evaluating the analgesic and pathologic effects of NSAID in fish is essential. To determine the biochemical, histopathologic, physiologic and behavioral effects of 3 NSAID, 48 rainbow trout underwent anesthesia with tricaine methanesulfonate and exploratory celiotomy and were randomly assigned to receive flunixin (0.5 mg/kg IM), ketorolac (0.5 mg/kg IM), ketoprofen (2 mg/kg IM), or saline. Clinical pathologic variables were assessed 1 wk before surgery and 48 h after surgery. Histopathology was performed to evaluate the healing of the incision, tissue reaction at the injection site, and potential organ toxicity. Physiologic and behavioral parameters, including weight, feeding, opercular rate, and vertical position in the water, were measured to establish parameters for identifying pain in fish. The difference between the pre- and postoperative phosphorus concentrations was greater in the flunixin group than the saline group and was the only pathologic difference between treatment groups. Histopathology of incision site, injection site, and internal organs appeared normal, and healing did not appear to be inhibited by the drugs used. The physiologic parameters of opercular rate and weight were consistent and may be helpful in identifying pain in fish in future studies, whereas feeding and vertical position in the water were unhelpful as indicators of pain in this rainbow trout surgical model. Overall, according to clinical pathology and histopathology, the use of ketoprofen, ketorolac, and flunixin at the dosages used in this study lack negative effects in rainbow trout undergoing surgery.