Blood coagulation is the defense system that maintains the integrity of the high-pressure closed blood circulatory system. After tissue injury, blood starts flowing into soft tissues or external bleeding occurs. To prevent excessive blood loss, the system, which includes platelets, endothelial cells, and coagulation protein plasma prekallikrein (also known as Fletcher factor), is called into play. Prekallikrein is of importance in the early phase of blood coagulation because it influences the rate of activation of factors XI and XII. In the absence of prekallikrein, factor XII is activated more slowly.3 Prekallikrein deficiency, also known as Fletcher trait, is a rare blood coagulation anomaly characterized by mild bleeding disorders.
Hereditary prekallikrein deficiency conditions are inherited through an autosomal recessive pattern. Severe deficiencies of prekallikrein may complicate surgical procedures. Prekallikrein deficiency has been described in association with Factor XII deficiency and von Willebrand's Disease and is generally diagnosed when evaluating a prolonged coagulation time with clinical history that is negative for a bleeding disorder. The condition has been reported in the Poodle, Miniature horses and Belgian horses. Specific treatment is not usually required, but transfusion with plasma is sometimes performed. Affected animals should not be bred because they are considered carriers of the trait.2
- The Merck Veterinary Manual. Congenital Coagulation Protein Disorders.
- Lowell Ackerman. Genetic Connection: A Guide to Health Problems in Purebred Dogs.
- Norman F. Cheville. Introduction to veterinary pathology.
- Veterinary Surgery: Small Animal: 2-Volume. Karen M. Tobias DVM MS DACVS, Spencer A. Johnston VMD DACVS