Assessment of method reliability and determination of reference intervals for rotational thromboelastometry in horses.
OBJECTIVE
To assess the measurement reliability of rotational thromboelastometry (ROTEM) measurements in horses, establish reference intervals for healthy horses, and evaluate the relationship between ROTEM variables, hematologic variables, and standard coagulation tests.


METHODS
Prospective observational study.


METHODS
University teaching hospital.


METHODS
Fifty healthy and 10 diseased adult horses.


METHODS
None.


RESULTS
Blood was sampled from 10 healthy and 10 diseased horses and samples were repeatedly analyzed to evaluate measurement reliability of various ROTEM variables. Four different ROTEM assays (ie, EXTEM, INTEM, FIBTEM, and APTEM) were run simultaneously under standardized conditions. The device-related, operator-related, and day-to-day variability for the majority of ROTEM variables was very low to low, as indicated by a coefficient of variation (CV) of < 15%. Most of test-retest variability of ROTEM variables appeared to be device-related. Blood samples from 50 clinically healthy horses were used to establish reference intervals for ROTEM variables. Multiple stepwise regression analyses identified associations of different ROTEM variables with hematocrit, total protein concentration, fibrinogen concentration, platelet count, prothrombin time, activated partial thromboplastin time, and thrombin time.


CONCLUSIONS
ROTEM is a feasible method to evaluate coagulation in horses. Its measurement reliability is acceptable, but device-related measurement variability has to be considered. Reference intervals are presented, but the influence of hematocrit, platelet count, and fibrinogen concentration may need to be taken into account when interpreting individual test results.
Clinic for Equine Internal Medicine, University of Zurich, Zurich, Switzerland.
Hannah K
HK
Junge
Equine Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
Simone K
SK
Ringer
Equine Department, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
Nathalie
N
Mayer
Clinic for Equine Internal Medicine, University of Zurich, Zurich, Switzerland. cschwarzwald@vetclinics.uzh.ch.
Colin C
CC
Schwarzwald
D000818:Animals; D001777:Blood Coagulation; D001780:Blood Coagulation Tests / Q000379:methods / Q000662:veterinary*; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D006470:Hemorrhage / Q000175:diagnosis / Q000662:veterinary; D006734:Horse Diseases / Q000097:blood / Q000175:diagnosis; D006736:Horses; D008297:Male; D010314:Partial Thromboplastin Time; D010976:Platelet Count; D011446:Prospective Studies; D011517:Prothrombin Time; D012016:Reference Values; D015203:Reproducibility of Results; D013916:Thrombelastography / Q000379:methods / Q000662:veterinary*
D005340:Fibrinogen
ROTEM; coagulation testing; equine; validation