Objective—To evaluate isoeugenol as an anesthetic agent in koi carp.
Animals—216 juvenile koi carp (Cyprinus carpio).
Procedures—Fish were randomly allocated to 9 groups of 24, and each group was randomly exposed to isoeugenol concentrations ranging from 0 to 500 mg/L. General activity, excitement, fin and gill color changes, opercular movement rate, loss of equilibrium, muscle tone, jaw tone, and handleability were assessed. Five fish from the control (0 mg/L), 200 mg/L, and 500 mg/L groups were randomly selected prior to anesthetic recovery and again 24 hours after recovery for euthanasia, gross necropsy, and histologic assessment of gills, internal viscera, and skeletal muscles.
Results—Mean ± SD interval to achieve stage 2 anesthesia with isoeugenol ranged from 22.4 ± 6.2 minutes at 20 mg/L to 0.25 ± 0.4 minutes at 500 mg/L, whereas the mean interval to stage 3 anesthesia ranged from 28.1 ± 3.9 minutes at 20 mg/L to 0.33 ± 0.48 minutes at 500 mg/L. With the exception of the 500 mg/L group, opercular movements were maintained throughout. Death was observed only in the 500 mg/L group, in which 50% of the fish either failed to recover or died within 24 hours after anesthetic exposure. There were no pathological differences between fish exposed to isoeugenol at 0 or 500 mg/L.
Conclusions and Clinical Relevance—Isoeugenol appeared to have a wide margin of safety with predictable dose-related effects. Concentrations of 40 to 80 mg/L induced anesthesia within 4 to 11 minutes and were considerably less than the concentration associated with fish death.
OBJECTIVE To describe a technique for endoscopic evaluation of the coelomic viscera of koi (Cyprinus carpio) and to evaluate the ability to visually examine coelomic structures by use of an approach cranial or caudal to the pelvic girdle.
ANIMALS 16 subadult koi.
PROCEDURES Koi were anesthetized with buffered tricaine methanesulfonate. Coelioscopic examination was performed via a ventral midline incisional approach cranial or caudal to the pelvic girdle. A 2.7-mm × 18-cm 30° oblique endoscope within a 4.8-mm operating sheath and infusion of saline (0.9% NaCl) solution was used. Ease of entry into the coelomic cavity and visual examination of structures were scored for each fish. Fish were euthanized 2 or 8 weeks after the procedure, and necropsy was performed.
RESULTS The coelioscopic procedure was tolerated well, and all koi recovered uneventfully. For all fish, ease of entry and visual examination scores of the liver, intestines, gonads, heart, and anterior kidney were satisfactory to excellent. Visual examination of the posterior kidney and swim bladder was satisfactory to difficult, whereas the spleen and gallbladder were not visually identified. No significant differences were noted in entry or visual examination scores between the cranial and caudal approaches or between sexes. Minor complications included mild hemorrhage, rupture of the gonadal capsule, formation of adhesions between the viscera and incision site, and delayed healing of the incision.
CONCLUSIONS AND CLINICAL RELEVANCE Diagnostic coelioscopy of koi appeared to be safe and effective. This procedure could have potential for use in examination of coelomic structures and disease diagnosis.