Objective: Large-diameter monopiles are the primary foundations for offshore wind turbines. However, in challenging marine hydrodynamic environments, flow disturbances around these monopiles often cause significant scour in the adjacent sandy seabed. This scour reduces the effective embedment depth, increases the length of the cantilever section of the monopiles, initiates sediment transport, and modifies the consolidation state of the underlying soil. These changes weaken monopiles' lateral bearing capacity and affect wind turbines' overall dynamic responses. Consequently, developing an accurate and efficient method to assess scour effects on the lateral bearing capacities and dynamic responses of monopiles is imperative. Methods: In this research, finite element models of pile-soil interactions after scour equilibrium were developed in Abaqus; these models integrate a cyclic dynamic hypoplastic constitutive model that captures the mechanical behavior of sand under complex loading paths and accounts for soil consolidation states. Turbulent wind loads and irregular wave loads acting on wind turbine foundations were computed using OpenFAST and Abaqus/Aqua, respectively. The numerical simulation unfolds in three phases: 1) The first phase involves assigning the initial stress fields and applying gravity loads to the complete pile-soil model to achieve geostatic equilibrium with the soil in a normally consolidated state. 2) The second phase involves removing soil elements within a predefined scour depth to simulate the unloading process, shifting the underlying soil to an over-consolidated state. 3) The third phase involves imposing the turbulent wind and irregular wave load on the monopiles to evaluate horizontal dynamic responses, accounting for scour effects. The pile-soil interaction model was validated using centrifuge test data. Based on this model, the soil flow mechanisms of monopiles under horizontal cyclic loads after scour equilibrium were analyzed, revealing the impacts of changing stress histories in remaining soils and local scour depths on the horizontal bearing capacity responses of cyclically loaded monopiles. Results: Numerical analysis results reveal the following key findings: 1) Scour significantly accelerates deformation accumulation in monopiles and reduces the lateral stiffness of pile-soil interactions. At identical scour depths, peak horizontal displacement at the mudline is twice as high for global scour compared to local scour. 2) Scour-induced changes in soil consolidation states enhance the remaining soil's shear strength and compressive resistance. Assessing post-scour horizontal displacement responses using pile-soil interaction stiffness derived from pre-scour soil parameters overestimates peak displacement by approximately 23%. 3) The influence of scour depth and lateral extent on pile-soil interactions is confined to a wedge-shaped failure zone surrounding the monopile. The zone's width and depth scale linearly with increasing local scour depth. Conclusions: The finite element analysis models of pile-soil interactions developed in this study are effective for evaluating scour impacts on the dynamic response of monopile foundations under cyclic loading. Unlike API and DNV standards, which only account for scour by simply reducing foundation embedment depth, this study highlights the critical role of scour-induced changes in soil consolidation state; incorporating them further reduces monopile displacement responses.