Assessment of hemostasis in hyperthyroid and euthyroid cats using two viscoelastic assays and platelet aggregometry

Abstract Background Hyperthyroidism in humans is associated with a hypercoagulable state and an increased risk of thromboembolism. Objective To evaluate hemostatic variables in hyperthyroid and euthyroid cats with the hypothesis that hyperthyroid cats will have evidence of altered hemostasis consistent with a potential hypercoagulable state. Animals Client‐owned hyperthyroid (n = 16) and euthyroid (n = 15) cats over 8 years of age. Methods Prospective observational study. Hyperthyroid and euthyroid cats were enrolled. Rotational thromboelastometry (ROTEM), whole‐blood platelet impedance aggregometry (WBPIA) and a point‐of‐care viscoelastic coagulation monitor (VCM‐Vet) were performed immediately after minimally traumatic venipuncture under sedation. Results Hyperthyroid cats had significantly higher values for variables as assessed by VCM‐Vet: A10 (34 [17‐47] vs 25 [17‐38], P = .003); A20 (39.5 [23‐55] vs 31 [21‐45], P = .003); and MCF (41 [24‐58] vs 35 [22‐49], P = .03). Hyperthyroid cats had significantly different values versus the euthyroid cohort as assessed by different ROTEM channels: increased A10, INTEM (61.5 [39‐75] vs 54 [23‐66], P = .007) and FIBTEM (18 [10‐35] vs 13 [2‐27], P = .01); increased A20, INTEM (68 [45‐78] vs 61 [30‐70], P = .006) and FIBTEM (17 [10‐34] vs 11 [2‐25], P = .002); increased MCF, EXTEM (72 [65‐81] vs 69 [34‐78], P = .04), INTEM (70 [45‐85] vs 62 [35‐71], P = .01) and FIBTEM (18 [13‐37] vs 14 [3‐27], P = .02); increased alpha angle, EXTEM (80 [68‐85] vs 76 [41‐84], P = .01); shortened CT, EXTEM (52.5 [29‐73] vs 60 [52‐92], P = .003) and FIBTEM (52.5 [16‐75] vs 65 [53‐165], P = .001); and decreased ML, FIBTEM (20 [1‐36] vs 33 [19‐59], P <.001). No significant differences were found with WBPIA. Conclusions and Clinical Importance The hyperthyroid cats in this study had evidence of altered hemostasis as assessed by 2 viscoelastic methodologies, and characterized by increased clot amplitude, firmness, and faster coagulation times vs euthyroid controls.