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Effect of citrate concentration on coagulation test results in dogs

Tracy Stokol BVSc, PhD, DACVP1,2, Marjory B. Brooks DVM, DACVIM3, and Hollis N. Erb DVM, PhD4
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  • 1 Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
  • | 2 Present address is 36 Connecticut Ave, North Natick, MA 01760.
  • | 3 Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
  • | 4 Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.

Abstract

Objective—To determine the effect of citrate concentration (3.2 vs 3.8%) on coagulation tests in dogs.

Design—Original study.

Animals—30 clinically healthy dogs and 12 dogs with hereditary hemostatic disorders.

Procedure—Blood was collected from all dogs directly into collection tubes containing 3.2 or 3.8% buffered citrate. Prothrombin time (PT), activated partial thromboplastin time (aPTT), and fibrinogen concentration were measured by use of 3 clot-detection assay systems (2 mechanical and 1 photo-optic). Factor VIII and factor IX coagulant activities (FVIII:C and FIX:C, respectively) were determined by use of a manual tilt-tube method and a mechanical clot-detection device.

Results—Significant differences were not detected in median PT, fibrinogen concentration, FVIII:C, or FIX:C between 3.2 and 3.8% citrate for any assay system. A significant prolongation in aPTT for 3.2% citrate, compared with 3.8% citrate, was found in 1 mechanical system.

Conclusions and Clinical Relevance—Citrate concentration does not significantly affect results of most coagulation assays, regardless of assay system. The aPTT was mildly influenced by the citrate concentration, although this was animal-, instrument-, and reagent-dependent. The choice of 3.2 or 3.8% citrate as an anticoagulant for coagulation tests has minimal influence on assay results in healthy dogs or dogs with hereditary hemostatic disorders. (J Am Vet Med Assoc 2000;217:1672–1677)

Abstract

Objective—To determine the effect of citrate concentration (3.2 vs 3.8%) on coagulation tests in dogs.

Design—Original study.

Animals—30 clinically healthy dogs and 12 dogs with hereditary hemostatic disorders.

Procedure—Blood was collected from all dogs directly into collection tubes containing 3.2 or 3.8% buffered citrate. Prothrombin time (PT), activated partial thromboplastin time (aPTT), and fibrinogen concentration were measured by use of 3 clot-detection assay systems (2 mechanical and 1 photo-optic). Factor VIII and factor IX coagulant activities (FVIII:C and FIX:C, respectively) were determined by use of a manual tilt-tube method and a mechanical clot-detection device.

Results—Significant differences were not detected in median PT, fibrinogen concentration, FVIII:C, or FIX:C between 3.2 and 3.8% citrate for any assay system. A significant prolongation in aPTT for 3.2% citrate, compared with 3.8% citrate, was found in 1 mechanical system.

Conclusions and Clinical Relevance—Citrate concentration does not significantly affect results of most coagulation assays, regardless of assay system. The aPTT was mildly influenced by the citrate concentration, although this was animal-, instrument-, and reagent-dependent. The choice of 3.2 or 3.8% citrate as an anticoagulant for coagulation tests has minimal influence on assay results in healthy dogs or dogs with hereditary hemostatic disorders. (J Am Vet Med Assoc 2000;217:1672–1677)