A 16-year-old unsexed blue-and-gold macaw was presented for a 5-day history of progressive swelling of the left tibiotarsus. The bird was weight bearing on the affected leg and otherwise healthy. Two firm 2-cm-by-2-cm masses were found on the medial and lateral aspects of the left tibiotarso-tarsometatarsal joint. The owner initially declined diagnostic testing, and the bird was treated empirically with trimethoprim–sulfamethoxazole and meloxicam.
The masses increased in size over the next 8 days, so diagnostic testing was pursued. Radiography revealed soft tissue thickening with no obvious bone or joint involvement. Fine-needle aspiration was nondiagnostic. CBC revealed a heterophilic leukocytosis with heterophilia and mild toxic changes in the heterophils. Serum chemistry profile was unremarkable other than changes consistent with striated muscle damage.
Seventeen days after initial presentation, the masses were considerably larger, and the bird was no longer weight bearing on the affected limb. Punch biopsy samples were collected, and histologic findings were consistent with soft tissue sarcoma. Limb amputation was performed 3 cm proximal to the masses. Histology confirmed an intermediate-grade soft tissue sarcoma with clean margins. Neoplastic cells were found in the bone marrow of the tibiotarsus.
The macaw recovered well, other than a mild episode of pododermatitis, but suddenly died of acute hepatic hemorrhage 32 months after surgery. No recurrence or metastasis of the soft tissue sarcoma was identified on necropsy.
The authors concluded that soft tissue sarcoma should be included as a differential diagnosis for rapidly growing masses in psittacines and that amputation is a treatment option for soft tissue sarcoma of the pelvic limb.