Abstract
Inflammatory diseases are common in companion dogs. Although white blood cell (WBC) count and C-reactive protein (CRP) are routinely used to assess systemic inflammation, their individual prognostic value remains limited. The erythrocyte sedimentation rate (ESR), reflecting red blood cell aggregation driven by plasma proteins, has long been applied in human medicine as both an inflammatory and prognostic marker. This study evaluated the prognostic utility of ESR in dogs, including clinically healthy and diseased populations. Associations between ESR, other inflammatory markers, and age were examined, and its role as an independent predictor of mortality and optimal clinical cut-off were determined. A subgroup of dogs meeting the systemic inflammatory response syndrome (SIRS) criteria were also analyzed to assess the latter's usefulness in acute settings. A total of 350 dogs were enrolled: 241 diseased and 109 healthy. ESR was measured using an automated analyzer. Receiver operating characteristic (ROC) curve analysis, expressed as the area under the curve (AUC), evaluated diagnostic accuracy, followed by Kaplan-Meier survival and Cox proportional hazard analyses. ESR values were significantly higher in the disease group than in the healthy group (p < 0.0001). ESR showed fair to good prognostic accuracy for mortality in both the overall cohort (AUC = 0.776 [95% CI: 0.709-0.842]) and the SIRS subgroup (AUC = 0.846 [95% CI: 0.747-0.946]). An ESR cut-off of 18 mm/h was associated with mortality in SIRS dogs with 87.5% specificity. In the multivariate analysis, ESR showed an independent association with mortality (hazard ratio 1.013 [95% CI: 1.004-1.022], p = 0.004). These findings support ESR as a practical and independent prognostic marker for risk stratification in dogs with systemic inflammation.