RUNTING OF DUCKLINGS ASSOCIATED WITH COCHLOSOMA-ANATIS INFECTION

Ducklings, especially common goldeneye (Bucephala clangula), experienc ing poor weight gain and delayed development were reported from a wate rfowl park during June and July of 1990. Runting was first noticed bet ween days 5 and 10 post-hatch in the ''brooder'' building, and althoug h ducklings appeared active and were feeding, they developed at a slow er rate than other members of their clutch. Many ultimately died of em aciation and gram-negative bacterial septicemia. Necropsies of affecte d ducklings revealed large numbers of the intestinal flagellate Cochlo soma anatis, in both the small and the large intestine; however, autol ysis impaired histological interpretation in many cases. Inoculation o f 1-day-old Muscovy ducklings with feces containing large numbers of C . anatis resulted in poor weight gain and delayed tail-feather develop ment compared with uninoculated control ducklings. Weight gain improve d after treatment with metronidazole. Cochlosoma anatis is associated with the runting syndrome observed in ducklings at the waterfowl park.