Short Title: Biomarker Assay for TCC Diagnosis in Canine Urine

16 Transitional cell carcinoma (TCC), the most common cancer of the urinary bladder in 17 dogs, is usually diagnosed at an advanced disease stage with limited response to chemotherapy. 18 Commercial screening tests lack specificity and current diagnostic procedures are invasive. A 19 proof of concept pilot project for analyzing the canine urinary proteome as a non-invasive 20 diagnostic tool for TCC identification was conducted. Urine was collected from 12 dogs in three 21 cohorts (healthy, urinary tract infection, TCC) and analyzed using liquid chromatography tandem 22 mass spectrometry. The presence of four proteins (macrophage capping protein, peroxiredoxin 5, 23 heterogeneous nuclear ribonucleoproteins A2/B, and apolipoprotein A1) was confirmed via 24 immunoblot. Of the total 379 proteins identified, 96 were unique to the TCC group. A statistical 25 model, designed to evaluate the accuracy of this multiplex biomarker approach for diagnosis of 26 TCC, predicted the presence of disease with 90% accuracy. 27