Survival following amputation and administration of single-agent carboplatin for treatment of appendicular osteosarcoma (OSA) in dogs was retrospectively examined. Records of 155 dogs with appendicular OSA treated with amputation and single-agent carboplatin were included from 14 centers. Any carboplatin dosage, number of doses, and protocol schedule were eligible for inclusion. The median disease-free interval (DFI) was 256 days. The median overall survival time was 307 days. Similar prognostic survival factors were identified in this study as reported in prior studies of canine appendicular OSA. Median DFI and survival were comparable to those reported in the original Bergman et al publication. Carboplatin treatment improves the survival probability in dogs with appendicular OSA compared to amputation alone and remains an acceptable alternative to adjuvant treatment with cisplatin.