Clinical Parelaphostrongylus tenuis infection in two captive American bison (Bison bison).

CASE DESCRIPTION: 2 juvenile (17 and 19 months of age) male American bison (Bison bison) were examined because of acute bilateral hind limb weakness and ataxia; 1 animal also had urinary incontinence. TREATMENT AND OUTCOME: Given the clinical signs and rapid deterioration in the condition of these 2 animals, obtaining a definitive diagnosis was considered essential to minimizing the risk of disease in the remaining bison herd and among other animals at the facility. Therefore, both affected animals were euthanized. At necropsy, no gross abnormalities were seen. Histologic examination of sections of the brains from both animals revealed mild to moderate multifocal aggregates of eosinophils and mononuclear cells in perivascular regions of the meninges and gray matter of the cerebrum, cerebellum, and brainstem. Systematic examination of multiple sections of brain and spinal cord revealed evidence of nematode sections and aberrant parasite migration. CLINICAL RELEVANCE: Findings suggested that CNS migration of Parelaphostrongylus tenuis in American bison may cause clinical signs. These findings have implications for the management of captive bison and free-ranging bison sharing ranges with white-tailed deer (Odocoileus virginianus), the definitive host, and elk (Cervus elaphus canadensis).

The effect of route of inoculation and challenge dosage on Riemerella anatipestifer infection in Pekin ducks (Anas platyrhynchos).

Riemerella anatipestifer is a gram-negative bacteria that can cause disease in a wide variety of wild and domesticated birds, especially waterfowl. The infection can be peracute, acute, or chronic. Although various routes of transmission have been proposed, to date, there is little information on the effects of route of transmission and challenge dosage on R. anatipestifer infection. Hence, the objective of this study was to determine the effect of route of inoculation and challenge dosage on R. anatipestifer infection and pathology. To achieve this objective, one hundred forty-seven 14-day-old white Pekin ducks (Anas platyrhynchos) were equally divided into 13 experimental groups (12 challenge and 1 control group). Each challenge group had 11 ducks. The control group had 15 ducks. Four routes of inoculation were evaluated (intranasal, oral, subcutaneous, and intravenous). Three dosage levels were evaluated for each inoculation route (10(2), 10(4), and 106 colony forming units [CFU]/ml). At the 106 CFU/ml dosage level, mortality was most associated with the subcutaneous (91%) and intravenous (82%) routes, followed by the nasal (18%) and oral (9%) routes. A unique pathologic lesion was found in the bursa of Fabricius and spleen of affected birds. Within the spleen and bursa of Fabricius, there were varying degrees of lymphoid depletion and necrosis within the cortical and medullary regions. These pathologic lesions have not been previously reported in ducks with R. anatipestifer infection.