Citation del Pozo J, Turnbull J, Crumlish M & Ferguson H (2010) A study of gross, histological and blood biochemical changes in rainbow trout, Oncorhynchus mykiss (Walbaum), with rainbow trout gastroenteritis (RTGE). Journal of Fish Diseases, 33 (4), pp. 301-310. https://doi.org/10.1111/j.1365-2761.2009.01122.x
Abstract The mechanisms behind the pathogenesis of rainbow trout gastroenteritis (RTGE) are still unknown. This study examined the macroscopic and microscopic changes in trout with RTGE (RTGE+), as well as the blood chemistry. A total of 464 rainbow trout were sampled from 11 sites in the UK, comprising 152 RTGE+ fish and 330 random, apparently healthy fish. A case definition for RTGE was assessed by the analysis of its agreement with three laboratory tests: histopathology, packed cell volume and kidney bacteriology. Cluster analysis indicated the presence of three distinct presentations within the population of RTGE+ fish. Cluster A included gross signs associated with moribund RTGE+ fish, and clusters B and C identified gross signs consistent with concurrent diseases, notably furunculosis, enteric redmouth and proliferative kidney disease. The information gained was used to select RTGE+ fish without concurrent disease for the analysis of RTGE pathogenesis with blood biochemistry. This analysis revealed a severe osmotic imbalance and a reduced albumin/globulin ratio as indicatives of selective loss of albumin. These findings are compatible with a protein losing enteropathy.