Case Report: Pasteurella anatipestifer as a Cause of Mortality in Semiwild Pen-Raised Mallard Ducks in South Carolina

The first case of anatipestifer infection diagnosed in South Carolina was in November 1971. The outbreak involved approximately 350 mallard ducks on a farm pond in Horry county. The group comprised approximately 50 older breeders and their young, hatched in incubators. The young were brooded under heat lamps and released on the pond when approximately 8 weeks old. Clinical signs of the disease included swimming aimlessly in circles, diarrhea, thick ocular discharge in some of the affected birds, tremors, and torticollis. The more severely affected birds appeared comfortable only when in dorsal recumbency. There was a progressive loss of equilibrium. Pasteurella anatipestifer was isolated from the brains of sick and dead birds. Control appeared adequate from chlortetracycline in an all-mash ration at 500 g per 909 kg of ration for 7 days. The origin of the infection is not yet determined.