THYMOMA IN A GERIATRIC RABBIT WITH HYPERCALCEMIA AND PERIODIC EXOPHTHALMOS

An 8-year-old rabbit was referred to an ophthalmologist because of int ermittent bilateral exophthalmos and prolapse of the nictitating membr anes. Both eyes could be retropulsed normally, and the exophthalmos wa s induced with ventroflexion. The rabbit had moderate hypercalcemia an d a large mediastinal mass that could be seen on thoracic radiographs. The rabbit's condition was unchanged for 5 months. It was reexamined because of weight loss and paroxysmal coughing and, at that time, was thin and tachypneic, and had reduced thoracic compliance. Thoracotomy was performed, and a 5-cm-diameter encapsulated mass, subsequently det ermined histologically to be thymoma, was removed. The rabbit was euth anatized after surgery because of complications. The periodic exophtha lmos and hypercalcemia in this rabbit were believed to be paraneoplast ic syndromes.