The Calgary Zoo maintains a 2-acre partially wooded exhibit adjacent to the Bow River that houses a flock of wild turkeys (Meleagris gallopavo), six mule deer (Odocoileus hemionus) and a pair of Sandhill cranes (Grus canadensis). On March 21, 2012, 1 of 15 wild turkeys was found deceased, and within a 48-hour period an additional five birds died. All birds were well fleshed and demonstrated no premonitory signs.
Necropsies identified mucous in the oral cavity, cranial erythema, gastrointestinal hemorrhage, mild cloacal prolapse, and miliary white foci throughout the livers. The coeloms and airsacs contained small amounts of serosanguinous fluid, and the lungs and spleens were congested. Prime differentials included fowl cholera (Pasteurella multocida), fowl typhoid (Salmonella enterica subs enterica serovar gallinarum), viscerotropic velogenic Newcastle disease (VVND avian paramyxovirus type 1), and fowl plague (highly pathogenic avian influenza virus). Birds were quarantined and stringent biosecurity safeguards were implemented.
Histopathology revealed multifocal necrosuppurative hepatitis, necrohemorrhagic pneumonia, and large numbers of intralesional coccobacilli. Air sacculitis, enterocolitis, and necroerosive proventriculitis were noted. Aerobic culture of lungs and livers yielded heavy growth of Pasteurella multocida.
The remaining birds were treated with trimethoprim-sulfadiazine (20 mg/kg q 12 h PO).a All remaining birds remained free of clinical signs, and activity levels in the flock increased over the next two days. After the initial outbreak, no additional wild turkey or other waterfowl mortalities were reported. Fowl cholera has been reported in some winters within the waterways of Calgary, occasionally causing profound mortality in overwintering waterfowl.1 Feeding practices in the exhibit have been altered to decrease the accessibility of both turkey and deer feed to wild birds and to assist in prevention of further outbreaks of this bacterial disease.
a. Uniprim® powder; MacLeod Pharmaceuticals Inc., Fort Collins, CO, USA
1. Lowes, N. 1990. Fowl cholera in overwintering mallard ducks. Can Vet J 31: 846.