The objective of this report was to describe the pathological changes in the urinary bladder of female rats naturally infected with Trichosomoides crassicauda. Forty eight 5 to 8 months of age female Wistar rats were studied. At necropsy uroliths were detected in seven animals (14.6%). Among the bladders that contained the parasite only three (6.3%) did not show any significant histological change and were considered normal, but on the contrary, three (6.3%) did contain papillomas and uroliths, four (8.3%) had uroliths associated with epithelial hyperplasia ranging from moderate to severe, and the remaining (79.2%) showed variable degrees of epithelial hyperplasia and inflammation without urolithiasis. It cannot be concluded whether irritation of the epithelium by the parasite itself plays a role in the formation of papillomas. However, the absence of papillomas in animals without uroliths suggests a positive relationship between uroliths and papillomas.
Rat; urinary bladder; Trichosomoides crassicauda; urolith; papilloma
