Hematology of Nile tilapia (Oreochromis niloticus) subjected to anesthesia and anticoagulation protocols

Abstract

Clinical hematology facilitates the diagnosis of disease and can act as a prognostic indicator of pathological conditions in fish. The aim of the present study was to evaluate hematological parameters of Nile tilapia (Oreochromis niloticus) subjected to different anesthetics and anticoagulants. Thirty apparently healthy fishes (average weight of 473 ± 35. 50 g and mean total length of 29. 33 ± 0. 37 cm), were selected from the local commercial fish farm in the Lages municipality (Santa Catarina, Brazil). The animals were randomly divided into three groups of 10. In two groups, anesthesia was induced with eugenol (70 mg·L -1 ) (EG) and Benzocaine hydrochloride (100 mg·L -1 ) (BG), respectively. Anesthesia was not administered to fish of the third group (CG/control group). Blood samples were obtained by venipuncture of the caudal vessels and placed into microtubes containing sodium heparin or Na 2 EDTA for further analysis. The results were analyzed by Sigma Stat for Windows, the paired t-test for significant differences between anticoagulants of the same group, and analysis of variance followed by the Tukey test for comparison of means between groups (p ≤ 0. 05). Most of the observed changes in the erythrogram were significantly higher for the anticoagulant heparin and benzocaine group in comparison to the control group. However, the values obtained for the leukogram were significantly higher for all groups subjected to the Na 2 EDTA anticoagulant, suggesting that heparin may cause cell clumping. The results suggest that the anesthetics under investigation effectively minimizes the effects of stress caused by handling and invasive procedures, and that the anticoagulant heparin causes less hemolysis in comparison to Na 2 EDTA for Nile tilapia. Thus, the hematological variations attributed to different anesthetic protocols and/or different anticoagulants should be considered for the species Oreochromis niloticus. Key words: Anesthetics, anticoagulants, hematology, Oreochromis niloticus, osmotic fragility ResumoA hematologia clínica é uma ferramenta que auxilia na realização do diagnóstico de doenças e pode atuar como um indicador prognóstico das condições patológicas de peixes. O objetivo deste estudo foi avaliar os valores hematológicos de tilápias do Nilo (Oreochromis niloticus) submetidas a diferentes anestésicos e amostras obtidas com diferentes anticoagulantes. Foram utilizados trinta peixes, com peso médio de 473±35,50 g e comprimento total médio de 29,33±0,37 cm, adquiridos de piscicultura comercial localizada no município de Lages (SC). Os animais foram divididos aleatoriamente em três grupos (n=10) conforme a forma de indução: grupo eugenol (GE) na concentração de 70 mg L -1 , grupo cloridrato de benzocaína (GB) na concentração de 100 mg L -1 e grupo controle (GC) sem o uso de anestésicos. As amostras de sangue foram obtidas por venopunção dos vasos caudais e acondicionadas em microtubos contendo heparina sódica ou Na 2 EDTA e posteriormente processadas. Os resultados foram avaliados pelo Sigma Sta...

Use of eugenol for anesthesia of lesser guitarfish Zapteryx brevirostris (Rhinobatidae)

“…In operations to colonize aquariums, it is not always necessary to anesthetize or sedate the fish. However, for some procedures, sedation is essential for minimizing the stress (Weinert et al, 2015) or physical damage that is caused through capture, biometry (Husen and Sharma, 2014) and transportation (Simões et al, 2011;Rucinque et al, 2016). For research or veterinary procedures, anesthesia or sedation to keep the animal unconscious or to relieve pain may be necessary (Ross and Ross, 2008).…”