Mesocestoidosis and multivisceral tetrathyridiosis in a European cat

This report describes the clinical, parasitological and pathological findings in a 6-year-old intact female European cat with thoracic and peritoneal tetrathyridiosis, characterized by genital involvement. Physical examination and X-ray evaluation revealed laboured breathing and several pulmonary nodules suggestive of cancer. However, necropsy demonstrated a parasitic aetiology of the disease. Histologically, multifocal granulomas were detected in the lungs, uterus and ovary. Parasitological examination permitted identification of the intestinal parasites as Mesocestoides lineatus, which was later confirmed by molecular examination. The larval forms in the peritoneal and chest cavity were identified as the second stage of the Mesocestoides sp. cestode named Tetrathyridia spp. The chronic injuries observed and the rapid course of the disease from the onset of the symptoms until death suggested a long period without clinical signs and indicate that overt disease can potentially be triggered by a failure of the immune system. The observed oophoritis and metritis identify tetrathyridiosis as a possible differential diagnosis in genital dysfunction.