Lipoma in the Mediastinum of a Prairie Dog (Cynomys ludovicianus).

A large, firm lipoma was found in the cranial mediastinum of a 3-year-old female prairie dog (Cynomys ludovicianus). It encompassed the carotid arteries, jugular veins, and thymus, and compressed the esophagus and trachea. Localized compression caused dysphagia, weight loss, and dyspnea, which eventually resulted in death. Most reports on prairie dogs involve their use in research on gallbladder contractility and its role in formation of cholesterol gallstones. There are few reports on naturally developing diseases in prairie dogs, and reports of neoplasia consist of only hepatocellular carcinoma and epiglottal fibrosarcoma. Intrathoracic lipomas have been reported as rare tumors in human beings, dogs, and rats. We describe here an intrathoracic lipoma in a prairie dog and information about this type of tumor in other species.