Submitted to: American Association of Veterinary Laboratory Diagnosticians
Publication Type: Abstract Only
Publication Acceptance Date: November 3, 2001
Publication Date: N/A
Technical Abstract: Tuberculosis due to Mycobacterium bovis infection is endemic in white-tailed deer in the northeastern portion of the lower Michigan peninsula. An understanding of disease pathogenesis will be necessary to effectively control or eradicate infection in this wildlife reservoir of M. bovis. Thirty-two, 9-month old white-tailed deer were inoculated with 300 CFU of M. bovis by the intratonsilar inoculation route. Three deer were euthanized and examined 2, 4, 6, and 8 weeks after inoculation. Five deer were euthanized and examined 3, 6, 9, and 11 months after inoculation. Gross and microscopic lesions were not seen until 28 and 42 days, respectively, after inoculation. Pulmonary involvement was first noted at 42 days after inoculation. Seventy-four percent of lung lesions were located in the left caudal, right caudal or right middle lobes. Pulmonary lesions at 42 days after inoculation consisted of subpleural aggregates of macrophages, multinucleated giant cells and small numbers of lymphocytes. Within the center of these cellular accumulations were small aggregates of neutrophils. Rarely acid fast bacteria were visible but always associated with the neutrophilic infiltrate. By the termination of the study, pulmonary lesions consisted of focally extensive, coalescing granulomas, composed of central necrosis surrounded by a zone of macrophages and multinucleated giant cells. A mantle of lymphocytes surrounded the granuloma. Staining by the Von Kossa method showed granular brown staining in the center of necrotic material. Masson's trichrome staining revealed slight, thin bands of collagen surrounding the granuloma.