Characteristics of hyperfibrinolysis in dogs and cats demonstrated by rotational thromboelastometry (ROTEM)

Hyperfibrinolysis (HFL) is a pathophysiological mechanism that has not been described in dogs or cats extensively. The aim of this study was to describe rotational thromboelastometry (ROTEM) parameters and underlying diagnosis in dogs and cats with HFL and evaluate association with bleeding diathesis. The ROTEM database was retrospectively searched for EXTEM (ROTEM activated with proprietary tissue factor) tracings with maximum lysis at 60min ≥15%. Concurrent ROTEM and plasma coagulation tests, thrombocyte number, diagnosis and survival to hospital discharge were extracted from medical records. Analysis of differences between dogs and cats and of factors associated with bleeding, fulminant HFL (clot breakdown within 30min) and survival to hospital discharge were performed. Hyperfibrinolysis was detected in eight cats presenting with haemoabdomen or haemothorax (n=4/8, 50%) and trauma (n=3/8, 38%) and in 36 dogs with angiostrongylosis (n=12, 33%), neoplasia (n=7, 19%), liver disease (n=4, 11%) and others including apparently healthy dogs (n=3, 8%). Hyperfibrinolysis was associated with prolonged EXTEM and APTEM (EXTEM with added apoprotein for inhibition of HFL) clotting time and decreased FIBTEM (EXTEM with added cytochalasin D for inhibition of thrombocytes) maximum clot firmness (MCF) in dogs and cats and with decreased EXTEM MCF in dogs. Bleeding dogs had significantly hypocoagulable EXTEM tracings. Fulminant HFL was associated with severe hypofibrinogenaemia in dogs (P=0.005) and was not associated with survival to hospital discharge. Evidence of HFL was demonstrated in dogs and cats with bleeding, trauma, parasitic and neoplastic disease. HFL is associated with late and weak clot formation.