Bacterial Kidney Disease (BKD) in Salmonids – Gross Pathology

Atlantic salmon (adult-1500 g) with BKD. Note the multiple granulomas in kidney. These severe lesions lead to renal failure

Bacterial kidney disease (BKD) is a chronic systemic infection of salmonid fish, the cause of which is the gram-positive diplobacillus, Renibacterium salmoninarum. Although BKD is most common in salmonids, both farmed and wild, R. salmoninarum is also found in other fish species, such as cyprinids and sablefish Anoplopoma fimbria. R. salmoninarum grows intracellularly in the phagocytic cells of the fish, resulting therefore in a largely granulomatous host response, although the early response to infection does involve significant numbers of neutrophils. Clinical signs and external lesions...

Tenacibaculosis in Fish – Gross Pathology

Figure 1. Rainbow trout displaying tail and peduncle lesions.

Tenacibaculosis is primarily a skin infection causing ulcerative dermatitis in a range of commercially important species worldwide. Three species belonging to the genus Tenacibaculum have been associated with the disease: T. dicentrarchi, T. finnmarkense, and T. maritimum.   These bacteria are all Gram-negative and filamentous.  In marine fish, the most common isolate is T. maritimum. There is variation in the external pathological signs of the disease, depending on the species and age of the fish involved. Different names have been used for this usually ulcerative dermatitis; they include salt water columnaris...

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