Eye tumor causing swelling and blindness in a hybrid macaw parrot

Abstract

An adult male green-winged () × military () hybrid macaw of unknown age was presented to the Texas A&M Veterinary Medical Teaching Hospital for evaluation of left periocular swelling, blepharospasm, and ocular discharge. Complete ophthalmic examination and B mode ocular ultrasonography were performed to evaluate the affected eye. Ocular examination revealed a blind left globe with exophthalmos, periocular swelling, diffuse corneal edema, and severe anterior fibrinous uveitis obscuring visualization of the intraocular structures. An ultrasound examination revealed a hyperechoic mass that filled the posterior segment of the globe. Focal discontinuity of the posterior sclera suggested scleral rupture. Enucleation with histopathology was recommended and performed 1.5 months later. Intraoperatively, a heavily pigmented and friable soft tissue mass extruded through the posterior sclera and extended into the orbit. Histologically, the mass was consistent with a malignant melanoma. The patient died 18 hours after the surgical procedure because of unknown complications. Postmortem examination did not identify evidence of metastasis. This study described the clinical appearance and histopathologic findings of a rare ocular neoplasm with extrascleral extension in a hybrid macaw. Although uncommon in psittacine birds, primary ocular melanocytic neoplasms may display features of malignancy with scleral or orbital invasion, or both.