Fibrinolysis: The Difference Between Dogs & Humans

Hyperfibrinolysis is a risk factor for bleeding; compared with humans, dogs have accelerated fibrinolysis. Antifibrinolytic drugs have been used in veterinary medicine to reduce postoperative hemorrhage in greyhound dogs, a breed at greater risk for postoperative bleeding complications. In humans, tranexamic acid (TEA) and ε-aminocaproic acid (EACA) are used to inhibit fibrinolysis. This study sought to determine the minimum plasma concentrations of TEA and EACA needed to completely inhibit fibrinolysis in canine blood after induction of in vitro hyperfibrinolysis. The concentration of EACA and TEA needed to inhibit fibrinolysis was 511.7 µg/mL and 144.7 µg/mL, respectively. This study confirmed that dogs were hyperfibrinolytic compared with humans, who require EACA and TEA concentrations of 122 µg/mL and 14.7 µg/mL, respectively, for complete inhibition of fibrinolysis.

The use of antifibrinolytic agents (TEA and EACA) has increased in veterinary patients for the treatment of observed or anticipated postoperative hemorrhage. Although evidence has supported that these drugs may reduce postoperative complications in dogs, ideal therapeutic blood concentrations and doses have not been established. This study demonstrated that higher concentrations of TEA or EACA were necessary to inhibit in vitro fibrinolysis in canine plasma compared with human plasma. This opens the door for further pharmacokinetic studies, which will bring veterinarians closer to establishing canine antifibrinolytic treatment protocols. Once dose ranges have been established, veterinarians will be better suited to assess therapeutic efficacy. Although antifibrinolytic treatment already shows promise in reducing postoperative hemorrhage in greyhounds, additional benefits (and possibly additional complications) may be observed when higher doses are used.—Julie Walker, DVM, DACVECC

Evaluation of tranexamic acid and ε-aminocaproic acid concentrations required to inhibit fibrinolysis in plasma of dogs and humans. Fletcher DJ, Blackstock KJ, Epstein K, Brainard BM. AM J VET RES 75:731-738, 2014.

This capsule is part of the One Health Initiative.