Eight normal puppies were inoculated with canine parvovirus (CPV). As a results, they were divided into two groups. Group I showed marked clinical signs, such as depression, anorexia, pyrexia, diarrhea, dehydration and vomiting. Group II showed only subclinical depression.
Severe leukopenia accompanied with lyrnphopenia and neutropenia was observed in all the puppies of group I till 5 days postinoculation (DPI). The total nucleated cell count of the bone marrow began to decrease 1 DPI and reached a minimum 5 DPI. In it, myeloid and erythroid cells decreased, and immature cells were very few or eventually disappeared. In group II, the leukocyte count showed a mild decrease over a period from 5 to 7 DPI.
HI antibody developed rapidly in both groups 5 DPI and its highest titer was reached 7 DPI.
Necropsy revelaed atrophy of the thymus, enlargement of the mesenteric lymph nodes, and congestion, thickening, edema and necrosis of the mucosal membrane of the small intestine in 3 of 8 puppies examined. Depletion and necrosis of lymphocytes were observed in lymphatic tissues. Intranuclear inclusion bodies were recognized in the small intestine, lymphatic tissues and bone marrow.
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