The establishment of reference intervals for the ClotPro thromboelastometry device in healthy dogs

Objective: To establish reference intervals using a new point-of-care thromboelastometry device in dogs for the extrinsically activated test (EX-test), intrinsically activated test (IN-test), fibrin polymerization test (FIB-test), ecarin test (ECA-test), and tissue plasminogen activator test (TPA-test) and to investigate the effects of storage time on the results.

Design: Prospective clinical study in 2022.

Setting: University teaching hospital.

Animals: Forty-eight healthy privately or university-owned dogs were prospectively enrolled and included on the basis of normal physical examination and normal baseline laboratory results (CBC, biochemistry profile, prothrombin time, and activated partial thromboplastin time [aPTT]).

Interventions: After a 30-minute storage time, the EX-test, IN-test, FIB-test, ECA-test, and TPA-test were performed on citrated blood samples. To determine the effect of storage time, 11 samples had the EX-test, FIB-test, and IN-test repeated 90 and 150 minutes after sample collection.

Measurements and main results: Ten thromboelastometry parameters were evaluated for each test. Reference intervals were calculated using the robust method for parametric data, and the robust Box-Cox transformed or nonparametric methods were used for nonparametric data. Increasing storage time resulted in more hypocoagulable tracings. A correlation was found between the IN-test and aPTT (r = 0.62, P < 0.0001). Other weak to moderate correlations were seen between thromboelastometry parameters and platelet count and hematocrit.

Conclusions and clinical importance: The development of reference intervals for the thromboelastometry device allows for the clinical use of this technology. Analyzing samples after a prolonged storage time of more than 30 minutes may result in erroneous results. Results may also be affected by an abnormal hematocrit or platelet count.