Diagnostic and Prognostic Value of Blood Ratios in Canine Splenic Hemangiosarcoma: A Multicentric Observational Study

Peripheral complete blood cell count (CBC) and blood ratios, including neutrophil-to-lymphocyte ratio (NLR), neutrophil-to-red blood cell ratio (NRR), and platelet-to-lymphocyte ratio (PLR), have been used in the diagnosis and prognosis of several cancers; however, their relevance in canine splenic hemangiosarcoma (HSA) remains to be investigated. This study investigated whether CBC, NLR, NRR, and PLR could be diagnostic and prognostic biomarkers in dogs with splenic HSA. Analyzing medical records of 154 dogs undergoing splenectomy from 2018 to 2022, we found that dogs diagnosed with splenic HSA (n = 63) had significantly higher neutrophil counts (14.9 ± 9.7 vs. 12.6 ± 9.6; <i>p</i> < 0.001), increased NRR (3.7 ± 2.6 vs. 2.7 ± 3.7; <i>p</i> < 0.001), lower platelet counts (145 ± 111 vs. 270 ± 213; <i>p</i> < 0.001), and reduced PLR (139.4 ± 160.0 vs. 259.9 ± 278.0; <i>p</i> < 0.001) compared to dogs with other splenic lesions. This study also identified a higher risk of relapse and mortality associated with increased NRR (<i>p</i> < 0.001 and <i>p</i> = 0.012, respectively) and an inverse relationship with PLR (<i>p</i> = 0.015 and <i>p</i> = 0.033, respectively), whereas NLR showed no significant association. The multivariate survival analysis identified NRR as an independent prognostic factor for DFI [hazard ratio (1.837); 95% confidence interval (1.147-2.942); <i>p</i> = 0.011], while for OS, the association did not reach statistical significance [hazard ratio (1.510); 95% confidence interval (0.985-2.314); <i>p</i> = 0.059]. These findings highlight the potential of NRR and PLR as biomarkers for assessing diagnosis and prognosis in canine splenic HSA, advocating for further validation in the future.