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Chromogenic assays for equine coagulation factors VII, VIII:C, IX, and X, and C1-esterase inhibitor
1Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
Insights
Automated human chromogenic assays successfully measure coagulation factors VII, VIII:C, IX, X, and C1-esterase inhibitor in horses. This method provides a reliable tool for evaluating equine hemostasis disorders.
Area of Science:
- Veterinary Hematology
- Clinical Pathology
- Coagulation Assays
Background:
- Manual chromogenic assays for specific coagulation factors are established in human medicine.
- Adapting these assays for equine plasma requires validation and automation for routine use.
- Accurate measurement of coagulation factors is crucial for diagnosing and managing bleeding disorders in horses.
Purpose of the Study:
- To adapt manual human chromogenic assays for coagulation factors VII (F.VII), VIII:coagulant (F.VIII:C), IX (F.IX), and X (F.X), and C1-esterase inhibitor (C1-INH) for automated analysis.
- To establish reference ranges for these coagulation factors in healthy horses.
- To assess the utility of these automated assays for evaluating equine hemostasis.
Main Methods:
- Human chromogenic assay kits for F.VII, F.VIII:C, F.IX, F.X, and C1-INH were adapted for a computer-assisted automated analyzer.
- Standards were prepared using pooled citrated equine plasma for F.VII, F.VIII:C, and F.X assays.
- Standards for F.IX and C1-INH assays utilized commercial pooled citrated human plasma.
- Assays were performed on plasma from 10 healthy horses to determine ranges and assess reproducibility.
Main Results:
- Mean activities in equine plasma were: F.VII (226 ± 19%), F.VIII:C (209 ± 31%), F.IX (149 ± 38%), F.X (88 ± 12%), and C1-INH (18.4 ± 8.4%).
- Intra-assay coefficients of variation (CV) ranged from 2.1% to 5.3%, while inter-assay CVs ranged from 3.8% to 22.0%.
- The automated assays demonstrated acceptable precision for routine clinical use.
Conclusions:
- Human chromogenic assay kits can be effectively automated for measuring F.VII, F.VIII:C, F.IX, F.X, and C1-INH activities in equine plasma.
- These automated assays provide a reliable method for routine assessment of coagulation factor activities in horses.
- The adapted assays are valuable for the evaluation of horses with hemostatic disorders.
Objectives:
To adapt manual human chromogenic assays for coagulation factors VII (F.VII), VIII:coagulant (F.VIII:C), IX (F.IX), and X (F.X), and C1-esterase inhibitor (C1-INH) for use with an automated analyzer, and to measure the activity of these proteins in horses.
Animals:
10 healthy horses were used to determine ranges for the assays. Pooled plasma for standards was collected from an additional 20 healthy horses.
Procedure:
A computer-assisted analyzer was programmed from the manual method for commercially available human F.VII, F.VIII:C, F.IX, F.X, and C1-INH chromogenic assay kits. Standards were prepared from pooled citrated equine plasma for the F.VII, F.VIII:C, and F.X assays, and from commercial pooled citrated human plasma for F.IX and C1-INH assays.
Results:
Mean +/- SD activities in citrated equine plasma from 10 horses were 226 +/- 19% for F.VII; 209 +/- 31% for F.VIII:C; 149 +/- 38% for F.IX; 88 +/- 12% for F.X; and 18.4 +/- 8.4% for C1-INH. Intra-assay coefficients of variation (CV) were 5.3% for F.VII; 2.1% for F.VIII:C; and 3.0% for C1-INH. Interassay CV were 5.7% for F.VII; 7.4% for F.VIII:C; 3.8% for F.IX; 14.4% for F.X; and 22.0% for C1-INH.
Conclusions:
Human chromogenic assay kits can be automated and used to measure F.VII, F.VIII:C, F.IX, F.X, and C1-INH activities in citrated equine plasma.
Clinical Relevance:
Human chromogenic assays can be routinely used to measure F.VII, F.VIII:C, F.IX, F.X, and C1-INH in horses, and may be useful in evaluation of horses with disorders of hemostasis.