A 9-month-old Standardbred filly was admitted to the veterinary teaching hospital for evaluation of a rightsided
facial swelling. Swelling over the right maxillary bone had been first noticed at 3 months of age. At that time,
the site had been drained, and the swelling resolved. Four months later (2 months prior to hospital admission),
the swelling developed again at the same location and gradually increased in size. Mild right-sided nasal and ocular
discharge and intermittent respiratory noise were also observed.