Hemostasis

Bleeding time measurement is a useful, but subjective and variable, in vivo test to evaluate hemostasis. There are several different bleeding times, including the buccal mucosal bleeding time (BMBT, a still used test for primary hemostasis in small animals), lip bleeding time (a still used test for primary hemostasis in large animals) and the cuticle bleeding […]

A variety of tests for platelet function are available. These tests assess all aspects of platelet activation, including adhesion, release reaction (P selection expression, ADP release), membrane flipping (phosphatidylserine exposure) and microvesiculation, activation of the fibrinogen receptor (GPIIb/IIIa), and aggregation. Genetic tests are available for specific defects, including CALDAG-GEF1 defect in Basset Hound thrombopathia and GPIIb/IIIa

Critical values Normal dogs and cats should have platelet counts close to or >200,000/µL; normal horses should have platelet counts of 100,000/µL or greater (foals have higher platelet counts than adults, usually >200,000/µL). Ruminants have higher platelet counts than horses (usually >400,000/µL, particularly in younger animals). Spontaneous bleeding, that can attributed solely to thrombocytopenia, does

There are a variety of drugs that affect all aspects of hemostasis; common ones will be mentioned in more detail below. This is no means an exhaustive list. Primary hemostasis Drugs associated with thrombocytopenia: Heparin, antineoplastic agents, gold compounds, propylthiouracil (an antithyroid drug), sulfonamides, and penicillin. Drugs for inhibition of platelet function: Aspirin, dazoxiben, dipyrimadole,

Numerous diseases and conditions affect hemostasis. Every animal with a bleeding disorder should be evaluated for underlying disease, especially older animals with a sudden onset of symptoms and no previous history of hemorrhage. A thorough drug history should also be taken as many drugs used to treat underlying diseases affect hemostasis. Liver disease The liver

Inherited deficiencies of inhibitors (antithrombin, protein C, protein S, plasminogen activator inhibitor) are quite uncommon in animals. In human patients, inherited deficiencies in inhibitors (or abnormalities in their targets that prevent inhibition) predispose the patient to deep venous or arterial thrombosis. Acquired abnormalities in inhibitors are seen in animals (please refer to inhibitor tests or antithrombin

Physiology Sources of vitamin K include K1, which is synthesized by plants and is present in food, and K2, which is synthesized by bacteria in the intestinal tract. Vitamin K1 and K2 are fat-soluble compounds. K1 is absorbed in the proximal small intestine and requires bile for absorption (being fat soluble) whereas K2 is absorbed

Inherited coagulopathies arise from mutations within genes responsible for synthesis or processing of active coagulation factors. In animals, deficiencies of intrinsic pathway factors (Factor XII, Factor XI, Factor IX and Factor VIII) are the most common. Some of these diseases are sex-linked (the gene is on the X chromosome) and usually occur in males. The

Von Willebrand disease (vWD) is the most common inherited disorder of hemostasis in both humans and dogs. It is due to a deficiency or abnormality in von Willebrand factor (vWf). Production of vWf Von Willebrand factor is a large multimeric glycoprotein that circulates non-covalently with factor VIII coagulant protein. It is produced in different cells and

Abnormalities in platelet function are called thrombopathias (also thrombocytopathy or thrombopathy). They can develop from increased platelet function (resulting in thrombosis) or decreased function (resulting in hemorrhage). Thrombopathias are more commonly recognized in dogs than other species. Inherited Inherited thrombopathias should be suspected in a young animal with a bleeding disorder, but showing normal results on