Masashi Yasuba

Histopathology of spontaneous lesions in beagles used for toxicity studies.

A histopathological study was carried out on spontaneous subclinical lesions in 86 beagle dogs employed in toxicity studies. The lesions found in a young adult group were compared with those in an older age group. Lesions detected more frequently in the older age group included acidophilic crystalline intranuclear inclusions in the liver and kidney, cell infiltration in the submaxillary gland, a tubular fatty change and glomerular lipid deposition in the kidney, atrophy and cyst formation in the thymus, siderofibrotic nodules in the spleen, and parafollicular cell hyperplasia in the thyroid. Focal mesothelial proliferation in the epicardium of the heart, intranuclear inclusions in the epididymis, focal granulomatous inflammation in the kidney, and aberrant pancreas in the gallbladder were noted each in 1 case. Granulomas possibly caused by parasitic infection were found in 21 cases (24.4%).