Multilobular osteochondrosarcoma of the canine skull: 16 cases (1978-1988)

The medical records of 12 dogs with multilobular osteochondrosarcoma (MLO) and examined at the Veterinary Teaching Hospital, Colorado State University from August 1979 to January 1987 were reviewed. Medical records of 1 dog with MLO and 3 dogs with MLO examined at the Ontario Veterinary College, University of Guelph and the Veterinary Medical Teaching Hospital, University of California, Davis, respectively, were also reviewed and included in the study. The mean age of affected dogs was 7.5 years, a single breed did not appear to be overrepresented, and males were affected as frequently as were females. All of the primary lesions affected either the mandible, maxilla, or cranium. Excision was the only treatment in 11 dogs, 2 dogs had radiotherapy in addition to excision, and 1 dog had radiotherapy and chemotherapy after excision. Twelve treated dogs had follow-up information available. Of the 12 treated dogs, 7 (58%) had local recurrence, with median time to recurrence of 14 months. Seven dogs (58%) developed metastatic disease after treatment, with median time to metastasis of 14 months. The median disease-free interval was 12 months, and the median survival time was 21 months. Excision with histologically complete surgical margins appeared to offer good opportunity for long-term tumor control. The role of adjuvant chemotherapy and radiotherapy in the management of MLO remains unclear.