Effect of surgical site infection on survival after limb amputation in the curative-intent treatment of canine appendicular osteosarcoma: a Veterinary Society of Surgical Oncology retrospective study

OBJECTIVE: To determine the influence of surgical site infection (SSI) on the median disease-free interval (DFI) and median survival time (MST) in dogs after amputation in the curative-intent treatment of appendicular osteosarcoma (OSA).

STUDY DESIGN: Multi-institutional retrospective cohort study.

ANIMALS: Fifteen dogs with OSA and SSI, and 134 dogs with OSA and no SSI.

METHODS: Medical records were reviewed, and dogs were included if the following criteria were met: histologic confirmation of OSA, no evidence of metastasis, ≥1 chemotherapy treatment, and available follow-up data. We used the definition of SSI from the Centers for Disease Control and Prevention. Kaplan-Meier estimates of median DFI and MST for the SSI and non-SSI groups were compared by log-rank test. Univariate and multivariate Cox proportional hazard regression analysis was evaluated for associations with DFI and survival.

RESULTS: The median DFI and MST of all OSA dogs were 236 days (95% CI, 181-283) and 283 days (95% CI 237-355), respectively. The median DFI of dogs with SSI (292 days) did not differ from that of dogs without SSI (224 days, P = .156). The MST of dogs with SSI (292 days) did not differ from that of dogs without SSI (280 days, P = .417). Failure to complete chemotherapy was associated with decreased DFI and survival (P < .001). Adjustments for chemotherapy completion found no effect of SSI on survival.

CONCLUSION: SSI did not influence the survival of dogs with appendicular OSA treated with amputation and curative-intent treatment.

CLINICAL SIGNIFICANCE: The extended survival associated with SSI after limb-spare surgery for OSA does not appear to be present after amputation. Interactions between the canine immune system and OSA warrant additional study.