Whole Blood Clotting,Clot Retraction and Prothrombin Utilization in Burros Following Total Body Gamma Radiation. ∗

Summary and Conclusions

1. Nine burros exposed to a lethal dose of whole body gamma radiation were observed. The burros had symptoms and pathologic changes characteristic of the irradiation syndrome. Four died during the first week and the remaining 5 died before the 30th post irradiation day. These 5 showed hemorrhagic symptoms. 2. There was a retardation of whole blood clotting time. A clotting defect was demonstrated in recalcified oxalated plasmas of burros tested 2 weeks after irradiation. 3. All irradiated burros developed a severe thrombocytopenia and a lessening of clot retraction was noted on the after 4th post irradiation day, with no clot retraction after the 16th day when the platelet count was approaching zero. 4. There was a pronounced diminution of prothrombin utilization rate after irradiation. The first change was noted 22 hours after irradiation or 3 hours after the animals were removed from the exposure field. 5. There was no demonstrable circulating anticoagulant. The possible relation of platelet concentration to the clotting defects is discussed.