Runting of ducklings associated with Cochlosoma anatis infection

Ducklings, especially common goldeneye (Bucephala clangula), experiencing poor weight gain and delayed development were reported from a waterfowl park during June and July of 1990. Runting was first noticed between days 5 and 10 post-hatch in the "brooder" building, and although ducklings appeared active and were feeding, they developed at a slower rate than other members of their clutch. Many ultimately died of emaciation and gram-negative bacterial septicemia. Necropsies of affected ducklings revealed large numbers of the intestinal flagellate Cochlosoma anatis, in both the small and the large intestine; however, autolysis impaired histological interpretation in many cases. Inoculation of 1-day-old Muscovy ducklings with feces containing large numbers of C. anatis resulted in poor weight gain and delayed tail-feather development compared with uninoculated control ducklings. Weight gain improved after treatment with metronidazole. Cochlosoma anatis is associated with the runting syndrome observed in ducklings at the waterfowl park.