Recurrent pyuria is associated with shorter progression-free survival in dogs with bladder urothelial carcinoma

Objective: To evaluate the association between pyuria and clinical outcomes in dogs. Methods: Data were collected from 2010 through 2025. Pyuria was defined as ≥ 5 WBCs/hpf in urine sediment. Dogs were stratified according to pyuria frequency (0, 1 to 2, or ≥ 3 episodes) and tumor size (< 3 or ≥ 3 cm). Progression-free survival (PFS) and overall survival were analyzed using Kaplan-Meier curves, log-rank tests, and Cox proportional hazards models. Results: 51 dogs diagnosed with bladder urothelial carcinoma (UC) were included. When stratified by pyuria frequency, dogs with ≥ 3 episodes had a significantly shorter median PFS than dogs without pyuria (175 vs 365 days), whereas dogs with 1 to 2 episodes did not differ significantly from the nonpyuria group. In the multivariable analysis, ≥ 3 pyuria episodes remained a negative prognostic factor for PFS (hazard ratio, 3.57; 95% CI, 1.27 to 10.04) even after accounting for the total number of urinalyses performed. Dogs with pyuria at initial diagnosis had a shorter median overall survival than the nonpyuria group (353 vs 531 days). Conclusions: Dogs with pyuria at initial diagnosis and frequent pyuria (≥ 3 episodes) during the entire treatment period had shorter PFS than dogs without pyuria. Clinical Relevance: This finding parallels observations in human medicine and suggests that pyuria may serve as a clinically useful marker of tumor progression in canine UC.