What is your diagnosis? A mass on the right tarsus in a rabbit

Abstract

A 12-year-old, neutered male American rabbit was presented to the University of Saskatchewan Veterinary Medical Centre for evaluation of a mass on the right tarsus, noted by the owners 2 months prior to presentation. On initial physical exam, the rabbit was bright, alert, and responsive. A painful, ulcerated, firmly attached 1.5 9 2 9 1 cm mass was located on the medial aspect of the right tarsus.The biochemical panel revealed moderate hypercalcemia and mild azotemia. Serum calcium concentrations of rabbits can be highly variable as almost all dietary calcium can be absorbed through the gut and the excess excreted by the kidneys. In rabbits, hypercalcemia can be diet-related or can occur with renal disease, secondary to neoplasia or volume contraction. The cause for hypercalcemia in this rabbit was unclear.A fine-needle aspirate of the mass was submitted for cytology ( Figure 1). A B Figure 1. Fine-needle aspirate of a mass on the right tarsus in a 12-yearold rabbit. Modified Wright-Giemsa. (A) 910 objective, (B) 9100 objective.