Intussusception caused by intestinal neoplasia in mature rainbow trout (Oncorhynchus mykiss, Walbaum 1792)

Abstract

The aquaculture industry is growing and includes the farming and breeding of more than 580 aquatic species worldwide. The rainbow trout (Oncorhynchus mykiss, Walbaum 1792) is the most commonly bred trout species in Hungary. As broodfish form the basis of most fish farms, investigation into tumours occurring in trout, although under‐researched, has proven to be a valuable and necessary field of study. During our investigation, we examined a broodstock of 3‐ to 6‐year‐old rainbow trouts (800) affected with idiopathic intestinal tumours (3%) which had consequentially led to ileus (40%). While performing necropsy, initial pathological observations showed intussusceptions. Tumours were discovered upon opening the body cavity, as well as metastasis forming in the livers and in the vessels of the gills. Histopathological and immunohistochemical tests allowed us to identify the neoplasms. The primary adenocarcinoma was found to have been developed within the intestines of the fish. The tumour tissue broke through the basal membrane and infiltrated the propria, protruding asymmetrically into the lumen of the mid‐intestines, causing it to narrow significantly. This subsequently led to passage disorders, invagination of the intestinal segment and finally the emaciation of the fish. Histopathological and immunohistochemical inspection of the tumour cells displayed a high mitotic index, confirming malignancy.

Rainbow trout (Oncorhynchus mykiss, Walbaum 1792) adenocarcinoma investigation with various diagnostic imaging techniques

“…Salmonid species can suffer from gastrointestinal tumours as has already been published by other authors (Bjørgen et al., 2019; Gombač et al., 2021). Adenocarcinomas in trout were usually observed at an older age in the broodstock (Brocca et al., 2021; Hoitsy et al., 2021). Tumours protruding into the cavity of the mid‐intestine can lead to reduced intestinal capacity and they could cause absorption problems, leading to weight loss in the individual.…”

“…Regular veterinary checks are important to reduce the animal and also the financial losses. Although neoplasms are not often observed in wild and farmed fish, the prevalence of tumours is higher in the broodstock in aquaculture and ornamental fish (Brocca et al., 2021; Hoitsy et al., 2021; Hyatt et al., 2013; Roberts, 2012). The reason for this can be the short lifespan and the understudied field until nowadays (Roberts, 2012).…”

Early-growth comparison of diploid and triploid rainbow trout (Oncorhynchus mykiss) in South Korea

“…In salmonids, alevins (hatched larvae) are accompanied with dense, yellowish liquid called yolk-sac containing globulins and oil droplets. At hatching, yolk-sac of the alevins could reach up to 75% of the entire body weight (Hoitsy et al, 2012). Alevins feed on this yolk-sac through absorption before and even before exogenous feeding began (Woynarovich et al, 2011).…”

“…According to Valente et al (2013), increased fry output is essential for the aquaculture sector to grow successfully and competitively. In rainbow trout aquaculture, hatching and development of sac-fry and rearing of fry are parts of works in the hatchery, in addition to selection of suitable broodfish and collection and incubation of eggs (Hoitsy et al, 2012). Proper larval rearing of this species ensues a high survival rate and maximum growth potential for a continuous supply of seeds for the grow-out culture.…”

>b<Caracterização de processos patológicos que acometem peixes-de-briga-Siamês (>i<Betta splendens>/i<) no estado de São Paulo>/b<

“…Embora os processos neoplásicos sejam frequentemente estudados em mamíferos, casos em peixes não são incomuns, havendo relatos em diversas espécies como Poecilia reticulata (FOURNIE et al, 2002), Poecilia velifera (DE STEFANO et al, 2012), Cyprinus carpio (STEGEMAN et al, 2010), Carassius auratus (MONES et al, 2021) e Betta splendens (LOMBARDINI et al, 2010) e Oncorhynchus mykiss (HOITSY et al, 2021).…”