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Updated: May 1, 2026
Ferric Chloride-induced Canine Carotid Artery Thrombosis: A Large Animal Model of Vascular Injury
Published on: September 7, 2018
The effects of protamine sulfate on clot formation time and clot strength thromboelastography variables for canine
Christopher J Bailey1, Amy M Koenigshof
1Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824.
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.
