Pathological studies on some viral diseases of cattle with particular emphasis on viral inducing abortion

Archival formalin fixed paraffin embedded tissues from 21 aborted fetuses and 3 mucosal disease affected calves that were submitted to the Departmentof Pathology and Microbiology, Atlantic Veterinary College, University ofPrince Edward Island, Canada between 1990 and 20 I 0 were examined. Theserepresented aborted fetuses that had at least one organ with positive signal byFAT for either BVDV or IBR were selected. A total of 74 paraffin blockswere examined. Gross and microscopic lesions were recorded. Of the 6BVDV suspected aborted calves, only one aborted calf (case 6) wasconfirmed by the demonstration of BVDV antigen in the pulmonary and thethymic tissues by immunohistochemistry using BVDV monoclonal antibody15C5. An amplicon size of 107 bp for BVDV was confirmed in the sameparaffin block of this case by RT-PCR. No significant gross lesions weredetected while microscopically lesions appeared as intramuscular edema withhyalinization of the muscle fibers of the heart. The thymus revealed markedlymphoid depletion with prominent edema in the interlobular septa which wasinfiltrated with leukocytes. Endotheliosis of few large blood vessels were. seen in the kidneys and thymus. The lungs showed edema in the pleura andinterlobular septa beside, oedema of the walls of the blood vessels andendotheliosis that might lead to complete obliteration of the lumen.Proliferation of alveolar macrophages and desquamation of the epitheliallining of the bronchioles was seen. The liver manifested prominent autolyticchanges. The hepatic capsule was thickened by loose connective tissue. Focalaggregations of macrophages, lymphocytes and fibroblasts were detected