Haematological assessment of rainbow trout, Salmo gairdneri Richardson, and Atlantic salmon, Salmo salar L., infected with Renibacterium salmoninarum

. Groups of rainbow trout, Salmo gairdneri Richardson, and Atlantic salmon, S. salar L., were infected with Renibacterium salmoninarum, injected with killed bacteria or starved. Selected red and white cell parameters were measured over a 35–day period. As a result of successful infection a typical granulomatous disease developed during which haematocrit, red cell count, haemoglobin, red cell diameter and the ratio of mature to immature erythrocytes all decreased. Red cell depletion was shown to be caused by their retention in the spleen and to be the cause of the observed splenomegaly. Increases in monocytes, thrombocytes and neutrophils were recorded in both infected groups.