Gross lesions and hematological changes in domesticated mallard ducklings experimentally infected with Cyathocotyle bushiensis (Digenea).

The digenean Cyathocotyle bushiensis has been associated with late summer fatalities of dabbling ducks in southern Québec. The objective of this study was to investigate the intensity- and time-dependent pathogenesis induced by experimental infection with this digenean in domesticated mallard ducklings. Lesions, hemorrhagic spots, plaques, and cores were observed in the ceca. Both affected tissue area and core weight increased with increasing intensity of infection. Magnitude of tissue damage increased with increasing duration of infection. Dye, administered intravenously, was found within the cecal lumen of infected ducks demonstrating increased permeability of the cecal wall to vascular products. The data suggest that infection was associated with decreased weight gain and a minor increase in body temperature. Elevations in hemoglobin concentration and packed cell volume were observed in some infected ducklings.