Objective—To determine the effects of protamine sulfate on clot formation time and clot strength thromboelastography variables for canine whole blood samples.
Animals—Blood samples obtained from 11 healthy dogs.
Procedures—Blood samples were collected from jugular veins of dogs into syringes with 3.2% sodium citrate (blood to citrate ratio, 9:1). Blood samples were divided into aliquots, and protamine sulfate was added to various concentrations (0 [control], 22, 44, and 66 μg/mL). Prepared samples were activated with kaolin (n = 8) or not activated (8), CaCl2 was added, and thromboelastography was performed. Reaction time (R), clot formation time (K), rate of clot formation (α angle), and maximum amplitude (MA) were measured.
Results—For kaolin-activated and nonactivated blood samples, protamine (66 μg/mL) significantly increased R and K and decreased α angle and MA, compared with values for control samples. Also, protamine (44 μg/mL) decreased MA in nonactivated blood samples and increased K and decreased α angle in kaolin-activated samples, compared with values for control samples.
Conclusions and Clinical Relevance—Results indicated protamine prolonged clot formation time and decreased overall clot strength in a dose-dependent manner; such effects may contribute to a hypocoagulable state in dogs. Kaolin-activated and nonactivated blood samples were appropriate for measurement of the effects of protamine on coagulation. Administration of protamine to reverse the effects of heparin should be performed with caution.