Soft-tissue tumors can be malignant or benign, and preoperative differentiation is important to help determine need for further diagnostics (eg, biopsy for staging, planning for surgical margins). Inflammation is a component of cancer biology. As such, this retrospective study investigated whether pretreatment albumin-to-globulin ratio (AGR) and neutrophil-to-lymphocyte ratio (NLR) could serve as biomarkers for distinguishing benign soft-tissue tumors (BSTTs) from soft-tissue sarcomas (STSs) in dogs. In addition, the relationship of NLR and AGR to histological tumor grade was assessed in dogs with STS. As these values are typically part of routine blood work, there is no additional cost in obtaining these ratios. The medical records of 178 dogs were identified for review. Twenty-two dogs with STS and 14 dogs with BSTT met inclusion criteria. The median NLR in the STS group was 9.640, which was significantly higher than in the BSTT group (4.261). The median AGR for the STS group was 0.846, which was significantly lower than in the BSTT group (1.033). While neither NLR nor AGR were useful as predictors of tumor grade in dogs with STS, it was concluded that NLR and AGR may be a cost-effective tool for pretreatment differentiation of STS and BSTT.