A 6-year-old spayed female golden retriever was presented to the Cornell University Hospital for Animals (CUHA) Oncology Service as a referral for an oral mass. The mass had been marginally excised using electrocautery approximately one month prior to presentation; histopathological analysis revealed acanthomatous ameloblastoma. Around two weeks after excision, the owners of the dog noticed a dime-sized mass at the same location, indicating local recurrence. At that point the dog was referred to CUHA for further diagnostic workup and possible treatment. On presentation the dog was bright and alert. Physical and oral examinations revealed a 1.5-cm in diameter, raised mass with irregular margins, on the buccal aspect of the caudal left mandible. A fine needle aspirate of the mass was performed; results were suggestive of ameloblastic fibroma. Further diagnostic workup was pursued including complete blood count (CBC), serum biochemical profile, urinalysis, and 3-view thoracic radiographs. The CBC revealed mild neutropenia and the serum biochemistry profile showed a mild hyperbilirubinemia. Results of other diagnostic tests were unremarkable. The patient returned 9 days later for an abdominal ultrasound, computed tomographic (CT) scan of the skull, and intraoral radiographs for surgical planning. The CT revealed a small soft tissue mass in the caudal left mandible with minimal bone lysis. A small amount of bone lysis associated with the tumor was seen on intraoral radiographs as well. After a discussion with the client comparing the risks and benefits of segmental mandibulectomy versus mandibular rim excision, which were the two surgical options for complete mass removal with adequate margins, the clients elected to pursue a mandibular rim excision. A mandibular rim excision, also known an alveolar ridge resection, was performed without complication. Histological analysis of the surgical specimen confirmed acanthomatous ameloblastoma with clean surgical margins. This presentation will discuss acanthomatous ameloblastoma and its corresponding differential diagnosis, and the indications and implications of mandibular rim excision as compared to other types of mandibulectomy.