Prekallikrein Deficiency

The prekallikrein deficiency, also known as Fletcher trait, is a rare blood coagulation anomaly caused by a genetic disorder, first described in 1965. Animals with prekallikrein deficiency have mild bleeding disorders. Hereditary prekallikrein deficiency conditions are inherited through an autosomal recessive pattern. The deficiency is generally diagnosed when evaluating a prolonged coagulation time with no other explanation and clinical history is negative for a bleeding disorder.

Blood coagulation is a host defense system that maintains the integrity of the high-pressure closed 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.

Plasma prekallikrein is of importance in the early phase of blood coagulation. Prekallikrein is synthesized in the liver and circulates in two forms. This blood plasma protein influences the rate of activation of factors XI and XII; that is, in the absence of prekallikrein factor XII is activated more slowly.³

Breeds at Risk

Prekallikrein deficiency has been described in association with Factor XII deficiency and von Willebrand's Disease. The condition has been reported in a Poodle, miniature horses, and Belgian horses. The diagnosis is usually made coincidentally when coagulation screening tests are performed.¹

Specific treatment is not usually required, but transfusion with plasma is sometimes performed if necessary. Affected animals should not be bred because they are considered carriers of the trait.²

1. The Merck Veterinary Manual. Congenital Coagulation Protein Disorders.
2. Lowell Ackerman. Genetic Connection: A Guide to Health Problems in Purebred Dogs.
3. Norman F. Cheville. Introduction to veterinary pathology.

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