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.