Diagnosis of primary hyperfibrinolysis and in vitro investigation of the inhibitory effects of tranexamic acid in a group of dogs with sarcomas - A pilot study.

Primary hyperfibrinolysis is not well characterised in canine cancer. This prospective case-control pilot study aimed to evaluate tissue plasminogen activator-modified thromboelastography (tPA-TEG) for diagnosis of primary hyperfibrinolysis in dogs with cancer and establish the in vitro therapeutic concentration of tranexamic acid (TXA). Nine dogs with sarcomas and normocoagulable thromboelastograms and 11 healthy dogs were included. For each a whole blood tPA-TEG, and four tPA-TEGs with added TXA in different concentrations were analysed. Lysis percentage at 30/60 min following maximal amplitude (LY30/60), clot lysis index (CL30/60), maximum rate of lysis (MRL), and total lysis (L) were investigated as diagnostic parameters of primary hyperfibrinolysis. In vitro TXA concentrations needed to inhibit 50% (IC50) and 90% (IC90) of the fibrinolytic potential were compared between groups. Significant primary hyperfibrinolysis (LY30 (P = 0.0001), LY60 (P = 0.003), CL30 (P = 0.01), and L (P = 0.02)) was observed in dogs with sarcomas. IC50 and IC90 of in vitro TXA for normalizing LY30 were 13.34 (SE 1.52) and 31.10 (SE 3.01) mg/L for dogs with sarcomas and 4.41 (SE 5.84) and 20.00 (SE 6.18) mg/L for healthy dogs. IC50 and IC90 for normalizing LY60 were 22.18 (SE 1.27) and 58.94 (SE 5.47) mg/L for dogs with sarcomas and 11.25 (SE 2.82) and 56.20 (SE 11.61) mg/L for healthy dogs. The IC50 for LY60 was significantly increased for dogs with sarcomas (P = 0.0003). Primary hyperfibrinolysis was documented by tPA-TEG in dogs with sarcomas. In vitro IC50 and IC90 for TXA were established. Clinical studies are required to establish therapeutic dosages in vivo.