Abstract Early symptoms of canine transitional cell carcinoma (TCC) are frequently assumed to be caused by other lower urinary tract diseases (LUTD) such as urinary tract infections, resulting in late diagnosis of TCC and decreased rates of survival. To determine whether miRNA can be used as non-invasive diagnostic biomarkers in this setting, we assessed miRNA expression in RNA extracted from urine and blood from dogs with clinically normal bladders (n = 28), LUTD (n = 25), and TCC (n = 18). Expression levels of 5 miRNA associated with TCC pathophysiology (miR-34a, let-7c, miR-16, miR-103, and miR-106b) were assessed by quantitative real-time PCR. Statistical analyses using ranked ANOVA identified significant differences in miR-103 and miR-16 levels between urine samples from LUTD and TCC patients (miR-103, fold change = 2.55, p = 0.015; and miR-16, fold change = 3.02, p = 0.002). However, logistic regression analyses determined miR-103, but not miR-16, can distinguish between canine LUTD and TCC patients (OR = 0.78 p = 0.031, AUC = 0.85). No statistically significant differences in miRNA levels were observed between blood samples from LUTD versus TCC patients. Expression levels of miR-34a trended with miR-16, let-7c, and miR-103 levels in normal urine samples, however, this coordination was completely lost in TCC urine samples. In contrast, cooordination of miR-34a, miR-16, let-7c, and miR-103 expression levels was maintained in blood samples from TCC patients. Our combined data indicate further investigation of miR-103 as a diagnostic urine biomarker for TCC, and investigation of the role of miR-103 as well as dysregulation of coordinated miRNA expression in bladder carcinogenesis, is warranted. Citation Format: Michael Kent, Allison Zwingenberger, Jodi Westropp, Laura Barrett, Paramita Ghosh, Ruth L. Vinall. MiRNA profiling of dogs with transitional cell carcinoma of the bladder using blood and urine samples. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1948.