Background: Chronic hepatitis (CH) in dogs is common and has the tendency to progress to liver cirrhosis (LC). Circulating microRNAs might have the potential as markers for disease progression. Objectives: To investigate whether concentration of specific microRNAs in serum correlate with the stage and grade of CH in Labrador Retrievers. Animals: Twenty-two Labrador Retrievers with histological CH (n = 8), LC (n = 7), and normal liver (NL, n = 7). Methods: In this retrospective study, serum concentrations of miR-122, miR-29a, miR-133a, miR-181b, and miR-17-5p were measured by quantitative real-time PCR and evaluated using univariate linear regression in dogs. A multivariate model was fit including the grade of hepatitis and the stage of fibrosis. Results: Of the 5 microRNAs, only circulating miR-122 and miR-29a were significantly associated with the grade of hepatitis and the stage of fibrosis. A positive correlation was identified between the grade of hepatitis with miR-122 (rs = 0.79, P <.001) and miR-29a (rs = 0.78, P <.001). Both miR-122 (rs = 0.81, P <.001) and miR-29a (rs = 0.67, P <.001) showed a significant positive correlation with the stage of fibrosis. MiR-122 concentrations were significantly higher in the CH (P <.01) and LC groups (P <.001) compared to the NL group. MiR-29a concentrations w
