Activated partial thromboplastin time and activated coagulation time in monitoring heparinized cats.

Cats were given heparin (IV or subcutaneously) at various dosages to determine the optimal dosage, route, and schedule for therapeutic anticoagulation. The activated coagulation time and activated partial thromboplastin time tests were used to evaluate heparin concentration. A dosage of 100 U/kg given IV produced an anticoagulation that was too brief and more potent than was desirable. Subcutaneous dosages of 250 and 375 U/kg produced therapeutically acceptable anticoagulation for 8 hours, whereas dosages of 500 and 1,000 U/kg causes an anticoagulation that was longer and more potent than was desirable. The activated coagulation time correlated well with the activated partial thromboplastin time in determining the degree of heparinization with certain limitations.