Physiological blood coagulation/clotting is an essential biological process that is initiated by vessel injury and includes a cascade of enzymatic reactions finalized by fibrin polymerization and clot formation. We utilize dynamic light scattering (DLS) imaging to monitor in vivo red cell mobility as an indicator of blood coagulation. In the course of the experiments, blood flow is arrested using mechanical occlusion, and then laser injury is applied. We demonstrate that the combination of laser injury with DLS imaging on occluded blood vessels (i.e., under static conditions) is suitable to detect even subtle changes of plasma viscosity in the circulatory system, which reflects the process of clot development. This approach is noninvasive and has a relatively simple and easy-to-use technical design. Thus, the proposed methodology provides a promising tool for investigating blood clotting within the vasculature.