Canis ISSN: 2398-2942

Hematology: prothrombin time

Synonym(s): PT, one-stage prothrombin time, OSPT

Contributor(s): Kathleen P Freeman

Overview

  • Evaluating extrinsic hemostasis + common pathway helps determine whether bleeding is due to a defect in hemostasis or other causes, eg trauma, ulceration, neoplasia, von Willebrand's disease.

Sampling

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Tests

Methodologies

  • Citrated plasma added to thromboplastin (with platelet factor 3) and calcium ions.
  • Time taken for fibrin to form is measured.

Availability

  • Most clinical pathology laboratories offer a basic hemostatic profile.

Validity

Sensitivity

  • More sensitive than activated clotting time (ACT).
  • Relatively insensitive since activity of clotting factor must be <30% to result in abnormal elevation.

Specificity

  • Does not require presence of platelets.
  • Useful for evaluating secondary hemostasis in dogs with severe thrombocytopenia.

Technique (intrinsic) limitations

  • Some methods/instruments used for human testing are not suitable for canine specimens. The instrument and method should be validated for canine specimens.

Result Data

This article is available in full to registered subscribers

Sign up now to purchase a 30 day trial, or Login

Further Reading

Publications

Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Couto C J (1999) Clinical approach to the bleeding dog or cat. Vet Med May, 450-459.
  • Sheafer S E & Couto C J (1999) Clinical approach to a dog with anticoagulant rodenticide poisoning. Vet Med May, 466-471.

Other sources of information

  • Kaneko J J, Harvey J W & Brass M L (eds) (1997) Clinical Biochemistry of Domestic Animals. 5th edn. Boston: Academic Press.
  • Jain N C (1993) Essentials of Veterinary Hematology. Philadelphia: Lea and Febiger.


ADDED