Effects of warfarin on vitamin K-dependent coagulation factors in Atlantic salmon and rainbow trout with special...

Plasma factor X (FX) was severely depleted in Atlantic salmon and rainbow trout after 18 days of oral warfarin administration; this response was further reflected in prolonged prothrombin time. Thus, both species require vitamin K for the maintenance of normal haemostasis. FX activity in controls of rainbow trout was 3- to 5-fold that of salmon. The FX of both species show several of the features of human FX: it is activated by RVV, inhibited by SBTI, inactivated in the presence of heparin, and adsorubs to insoluble barium precipitates. Rainbow trout sustained warfarin poisoning better than did salmon, with mortalities occurring 8 days later in trout. After 18 days all remaining fish had developed a severe haemorrhagic anaemia with anisocytosis, poikilocytosis, leucopenia, and thrombocytopenia.