Association Between Pre-Transfusion Systemic Inflammatory Response Syndrome and Transfusion-Associated Adverse Events in Dogs: A Retrospective Study

Blood transfusion is an important supportive therapy in critically ill dogs, but transfusion reactions (TRs) remain a clinically relevant complication. This retrospective study evaluated whether pre-transfusion systemic inflammatory response syndrome (SIRS) was associated with transfusion-associated adverse events in dogs. Medical records of dogs receiving red-cell-containing blood products at a veterinary referral hospital in the Republic of Korea between December 2023 and May 2026 were reviewed. Among 146 transfusion episodes from 100 dogs, 142 episodes with evaluable primary outcomes were included in the primary outcome analysis. Transfusion-associated adverse events were identified more frequently in the SIRS group than in the No SIRS group (32.7% vs. 11.4%; p = 0.007). In univariable logistic regression, SIRS was associated with increased odds of the primary outcome (OR, 3.78; 95% CI, 1.36–10.51; p = 0.011). In a patient-clustered multivariable generalized estimating equation (GEE) analysis, the adjusted OR remained elevated at 3.57, although the association did not reach statistical significance (95% CI, 0.98–12.98; p = 0.053). Each additional fulfilled SIRS criterion was associated with increased odds of the primary outcome (OR, 1.63; 95% CI, 1.10–2.41; p = 0.014). However, the association was attenuated and was not statistically significant in sensitivity analyses using stricter outcome definitions based on imputability and independent re-adjudication. These findings suggest an association between pre-transfusion SIRS and clinically suspected transfusion-associated adverse events under the broad retrospective primary outcome definition, but the results were sensitive to the level of diagnostic certainty required for outcome classification. The findings should therefore be considered hypothesis-generating and require confirmation in prospective studies using standardized reaction definitions and blinded outcome assessment.