Diagnoses of non-infectious diseases in Rachycentron canadum and Paralichthys orbignyanus bred in captivity

Author: Marta da Costa Klosterhoff (Currículo Lattes)
Supervisor: Dr Luis Alberto Romano
Co-supervisor: Dr Luís André Nassr de Sampaio

Abstract

Histopathological studies are tools of great importance for analysis of normal and pathological tissues. The most frequent causes of diagnostic errors are inadequate tissue fixation and poor quality of histological material. In addition, there is a shortage of studies evaluating “post mortem” changes in fish. In view of the need for knowledge about the main “post mortem” changes that occur until the time of fixation, this work seeks to demonstrate the main changes in sole tissues after different fixation times. It was concluded that the ideal time for the collection of biological material for histological analysis should not exceed one hour after death. Fish can develop non-infectious diseases, of the metabolic, neoplastic and nutritional type, as found in the species under study,Rachycentron canadum and Paralichthys orbignyanus. Through this study it was possible to describe the diagnosis of three non-infectious diseases, including nephrocalcinosis and the presence of kidney stones in bijupirás. Macroscopically, an increase in kidney size was observed, with the presence of several lithiasic structures grouped in the renal parenchyma. Given the factors that can contribute to the occurrence of the disease in breeding environments, it was not possible to pinpoint the real cause of the appearance of lesions in fish, making it necessary to investigate with research on predisposing factors. Within the group of non-infectious diseases, a hematopoietic neoplasm in bijupirá, classified as type B renal lymphoma,demonstrated by neoplastic cells expressed by the CD20 receptor not expressing receptors for type T lymphoma (CD4 and CD3). Another report of neoplasia, described as sclerosing hemangioma on sole, tumor samples were collected for histopathological analysis. In macroscopic analysis, a lesion with a congestive aspect, with an irregular surface and rigid consistency was observed, located in the maxillary region, with abrasions and hemorrhagic foci, which may be linked to trauma caused by shocks with the walls and bottom of the tank. In histological sections, hemorrhagic foci were observed, in addition to accumulation of fibrous tissue surrounding vascular structures, among other changes. The etiology of this neoplasm is unknown, but the fact that the animal remained in a breeding system for many years,may have contributed to the appearance of this type of injury, in addition to the mechanical factor.

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