Introduction

Osteosarcoma commonly was radioresistant tumor. Exenteration with partial orbitectomy were recommended for orbital osteosarcoma. No report of radiotherapy in combination with exenteration and partial orbitectomy for canine orbital osteosarcoma has been published.

Objectives

To present the efficacy of surgery with palliative radiation therapy for treatment of orbital chondrogenic osteosarcoma in a cocker spaniel.

Methods

An 11-year-old female cocker spaniel dog presented with a history of globe displacement at the right eye for 3 months. Ophthalmic examination revealed exophthalmos, third eyelid protrusion and increased intraocular pressure OD. Computed tomography finding revealed mass effect at right retrobulbar, zygomatic, and temporal area. Right zygomatic and temporal bone lysis were seen. Cytological examination revealed spindle cell carcinoma. Physical examination, hematology and blood chemistry results were in normal limits. Exenteration with zygomatic arch removal was performed.

Results

During surgery, a firm 10 cm 2 lobe mass adhesive with mandible was found to locate at retrobulbar area OD. Histopathological finding revealed chondrogenic osteosarcoma. Palliative radiotherapy with the 6 fractions of 6 Gy on days 0, 7, 14, 21, 28 and 35 was performed.

At one, four, eight and eleven months follow-up after radiotherapy, the mass was gradually reduced in size and finally stable. The dog has been alert with no enlargement of the orbital mass for more than one and a half-year follow-up period.

Conclusions

Exenteration and partial orbitectomy combined with palliative radiotherapy was effective for orbital chondrogenic osteosarcoma management in this dog for at least one and a half year.