A rapid and sensitive method for the confirmatory analysis of 8 synthetic corticosteroids (betamethasone, dexamethasone, prednisolone, 6 methyl prednisolone, triamcinolone, flumethasone, beclomethasone, fluocinolone acetonide) is proposed. The method is useful for detecting illegal treatments in different animal species. It consists of an extraction and clean-up using the Quick Easy Cheap Effective Rugged Safe (QuEChERS) strategy. Quantitative determination is achieved by ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry with heated electrospray ionization in negative mode. Quantification is performed using surrogate matrix matched standard calibration curve with dexamethasone-D4 as the internal standard. The method was validated for analyzing liver samples according to the criteria established by Decision 2002/657/EC. Linearity was assessed in the 1-10 μg kg-1 range and linear correlation coefficients were over 0.99 for all the analytes. CCα ranged from 0.04 to 0.16 μg kg-1 for substances without maximum residue limit. The method allows confident quantification and confirmation of corticosteroids in liver samples, and its simplicity makes it suitable for analyzing large numbers of samples.