Coagulation properties of fresh-frozin canine plasma during prolonged storage

Coagulation properties of fresh platelet-poor canine plasma from 20 dogs were examined before freezing and after storage at intervals of up to 1 year. Prothrombin time and factor V activity did not change in frozen plasma when compared with data obtained after plasma was stored 1 week. When compared with that of fresh plasma, activated partial thromboplastin time shortened and factor VIII activity decreased after freezing and thawing of fresh plasma after 1 week, activated partial thromboplastin time in fresh-frozen plasma gradually shortened during the year of storage. Factor viii activity increased in the first 4 months of storage, but gradually decreased by 1 year.