Objective: To describe modifications to the lateral orbitotomy for surgical excision of tumors affecting the frontal, parietal, palatine, or temporal bones. Study design: Case report. Animal: A 5-year-old female spayed American pit bull terrier. Methods: The dog presented for excision of a bone tumor affecting the right frontal and parietal bones. A modified lateral orbitotomy was performed with combined partial zygomatic arch and vertical ramus ostectomies to increase working space and allow drilling of the calvarium ventral to the mass. Results: The dog tolerated the procedure well, and there were no complications from either the ostectomies or the craniectomy. Histopathological examination was consistent with complete excision of an osteoma. The dog survived 2 years with no recurrence and was euthanized due to an intestinal mass. Conclusion: The lateral orbitotomy approach can be modified with combined partial zygomatic arch and vertical ramus ostectomies to increase exposure and working space for resection of tumors affecting the frontal, parietal, palatine, or temporal bones.