Abstract: The stability of hemostatic proteins, including coagulation factors II, VII, VIII, IX, and X and von Willebrand factor (vWf), in canine fresh frozen plasma (FFP) units stored for up to 1 year was studied. Plasma units from 7 donor dogs were subjected to 4 treatments following collection, including storage at −30°C for 3 months, 6 months, and 1 year and storage at −20°C for 6 months. Coagulant factor activity and vWf concentrations were measured at these times. Significant differences between prestorage and poststorage values were noted for factors VIII, IX, and X, and vWf. Differences seemed to be least pronounced for plasma stored for 3 months; however, a significant interaction between prestorage and poststorage differences and the 4 treatment groups could not be demonstrated. On the basis of factor content in the present study, 15–20 mL/kg of FFP stored for up to 1 year was capable of providing approximately 10–15 U/kg of vWf and factors VIII, IX, X, and II, whereas 10 mL/kg FFP provided at least 10 U/kg of factor VII.