Fibrosing granulomas in the equine liver and peritoneum: a retrospective morphologic study

Fibrosing granulomas were found in the liver and occasionally on the intestinal and diaphragmatic serosae and in the lung of 11 horses submitted for necropsy. Although these granulomas were considered incidental findings in most of the horses, they had caused liver failure in 1 horse. The granulomas typically were characterized by a dense collagenous core that frequently was mineralized. The periphery contained a rim of inflammatory cells. Only in 1 of the 11 horses was there evidence of an egg shell suggestive of schistosomes. Schistosomal eggs were not detected in the feces of the horses. The typical architecture of the granulomas combined with the occasional finding of a residual egg led to the circumstantial conclusion that the fibrosing granulomas were the result of chronic schistosomiasis of undeterminable origin.