Taenia taeniaeformis-induced Metastatic Hepatic Sarcoma in a Pet Rat (Rattus norvegicus)

An approximately 683-g intact adult male pet rat (Rattus norvegicus) of unknown age was presented to the veterinarian by its owner with a complaint of lethargy and anorexia. Physical examination findings consisted of an enlarged abdomen and a large cranial abdominal mass strongly suggestive of neoplasia. Because of a poor prognosis, the owner refused additional diagnostic tests and the rat was euthanized. A necropsy was performed, and the findings consisted of a large, irregularly shaped mass that replaced a large portion of the liver. Multiple metastases were present on the peritoneal surfaces of other abdominal organs. Cestode larvae consistent with Taenia taeniaeformis were within cystic cavities in the center of the hepatic mass and in the remaining liver tissue. The clinical and postmortem gross and microscopic findings were consistent with metastatic hepatic sarcoma induced by T taeniaeformis.