Circannual changes in blood coagulation factors and the effect of warfarin on the hedgehog Erinaceus europaeus.

Levels of blood coagulation factors were measured monthly in hedgehogs kept at 20 degrees C under a natural-light schedule for 1 yr using prothrombin time and the P & P method. Hedgehogs display a circannual cycle of blood coagulation factors in the absence of temperature cues, with high levels corresponding to the active period and low levels corresponding to the hibernation period. Ten hedgehogs and ten guinea pigs were treated with clinical doses of warfarin and blood coagulation factors measured. Warfarin caused a similar decrease in vitamin K-dependent blood coagulation factors in both species.