Clinical Changes Caused by the Liver Fluke Metorchis conjunctus in Cats

Abstract

Cats infected with metacercariae of the fluke Metorchis conjunctus were followed clinically through their infection. Cats given 200 metacercariae showed few symptoms. All the cats passed ova on the 17th day. Three hundred metacercariae caused diarrhea, icterus, discolored urine, green feces and eosinophilia after 18 to 21 days. Eosinophilia, leucine aminopeptidase and alanine aminotransferase were elevated and remain the best indicators for metorchiasis. The hematological and serological abnormalities resolved rapidly and were absent from cats with chronic infection. Acute lesions (<32 days) were confined to the biliary trees with extensive epithelial exfoliation, fibrosis, and pus from necrosis, tissue feeding by the worms and pressure atrophy. Chronic infections (32 to 150 days) caused hyperplasia of the bile epithelium, proliferation of connective tissues, and fibrosis of the perilobular areas. Intense eosinophilic infiltrates were replaced by mononuclear cells. Granuloma formation around an ovum was seen in one cat 719 days after infection. Adult worms established preferentially in the left lateral lobe and never in the caudal lobe. No gall bladder involvement was found even in heavy infections.