Blood urea nitrogen-to-albumin ratio predicts mortality in dogs with pyometra

Pyometra is a common reproductive disorder in intact female dogs and can progress to sepsis and multi-organ dysfunction. Accurate prognostic indicators are needed to guide clinical management. The blood urea nitrogen-to-albumin ratio (BUN/ALB) has been reported as a prognostic marker in human sepsis but has not been evaluated in canine pyometra.

To evaluate the prognostic value of the BUN/ALB in canine pyometra before and after surgery.

In this retrospective study, BUN/ALB was compared among survivors, non-survivors, and healthy dogs. The BUN/ALB was calculated as blood urea nitrogen (mg/dL) ÷ albumin (g/dL). Analyses included one-way analysis of variance with the Holm-Sidak post hoc test, Mann-Whitney tests, Jonckheere-Terpstra trend analysis, and receiver operating characteristic (ROC) curve analysis.

Preoperative BUN/ALB was higher in dogs with pyometra than in healthy dogs, with the highest values in non-survivors. ROC analysis showed an area under the curve (AUC) of 0.86 and an optimal cut-off of 8.935 (sensitivity of 73.08%, specificity of 90.91%). Postoperatively, the BUN/ALB remained higher in non-survivors (AUC, 0.81; cut-off, 8.445; sensitivity, 68.28%, specificity, 83.33%).

The BUN/ALB was significantly associated with mortality in dogs with pyometra both pre- and postoperatively. The BUN/ALB may serve as a simple, inexpensive, and readily available prognostic marker to support clinical decision-making in canine pyometra.