Studies on the pathology of bacterial kidney disease (Renibacterium salmoninarum) in coho (Oncorhynchus kisutch) and Atlantic salmon (Salmo salar)

• Main Author: Raverty, S A
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: University of Stirling 1992
• Subjects: Renibacterium salmoninarum; Coho salmon; Atlantic salmon; Fish culture Canada; Canada; Salmo salar
• Online Access: http://hdl.handle.net/1893/29416; http://dspace.stir.ac.uk/bitstream/1893/29416/1/Raverty.pdf

With the intensification of the aquaculture industry along the west coast of Canada, there has been a concomitant increase in the prevalance of bacterial kidney disease (BKD) (Renibacterium salmoninarum)(Rs) in production and government hatchery facilities. Due to the paucity of information on the pathogenesis and epizootiology of Rs, treatment and control measures have been confounded and emergance of BKD exacerbated. Initially, to enhance specificity over conventional histochemistry for demonstration of Rs in histological sections an avidin biotin conjugated immunoperoxidase technique was developed for us to monitor the histopathological manifestation of BKD. To ascertain the temporal and spatial hlstogenesis of BKD. coho (Oncorhvnchus kisutch) and Atlantic (Salmo salar) salmon ware challenged experimentally by intraperitoneal injection and naturally by cohabitation with Rs-innoculated fish than serially sampled. Histopathology revealed lesions consistent with past case reports and investigations, as well as previously undescribed manifestations including, inflammatory call kinetics in the renal perivascular compartment, cresentic glomerulonephritis, extrarenal dissemination (via septic emboli or direct extension), and ovarian follicular cell accumulation of Rs. Pseudocyst formation, renal interstitial hyperplasia and meningoencephalitis were also characterized. The granulomatous response in coho salmon was predominantly histiocytic, whereas, in Atlantic salmon a tuberculoid response was more apparent. In either species a profound call mediated immunity was adduced. To further resolve the nature of the inflammatory response, coho and Atlantic salmon were immunosuppressed by administration of suprapharmacologic doses of glucocorticosteroids. On challange with Rs both species incurred an earlier onset and greater rate of mortality than immunocompetent cohorts. The granulomatous response appeared irregular and expansive with exuberent intra- and extracellular Rs growth. These observations may be attributed to ...