Hyperfibrinolysis is a risk factor for bleeding. Antifibrinolytic drugs have been used in veterinary medicine to reduce postoperative hemorrhage in greyhounds, a breed at greater risk for postoperative bleeding complications. In humans, tranexamic acid (TEA) and ε-aminocaproic acid (EACA) 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 are hyperfibrinolytic compared to humans.