Prekallikrein Deficiency

Other Names: Fletcher factor deficiency, Fletcher trait
Affected Genes: KLKB1
Inheritance: Autosomal Recessive
Mutation: chr16:44501415 (canFam3): T>A

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Common Symptoms

Prekallikrein Deficiency is a rare inherited blood disorder affecting dogs, including a Shih Tzu. Prekallikrein is a protein that is part of the blood clotting process, and when deficient, increases the time for blood to clot. The Shih Tzu reported with this condition did not show increased incidence of Hemorrhage however, recognizing a congenital cause for increased blood clotting times is important because it can be associated with clinically important diseases. Dogs with this disorder can have severe bleeding if they have concurrent deficiencies in other proteins required for normal blood clotting. Dogs with a bleeding disorder may bruise easily, have frequent nosebleeds and exhibit prolonged bleeding after surgery or trauma. Due to the mild nature of this disorder, affected dogs may not be identified until a surgery is performed or trauma occurs at which time excessive bleeding is noted. Veterinarians performing surgery on dogs that are known to have prekallikrein deficiency should have ready access to blood banked for transfusions. Most dogs with this condition will have a normal lifespan despite increased blood clotting times.

Breed-Specific Information for the Shih Tzu

The Mutation of the KLKB1 gene associated with prekallikrein deficiency has been identified in a Shih Tzu, although its overall frequency in this breed is unknown.

Testing Tips

Genetic testing of the KLKB1 gene in Shih Tzu will reliably determine whether a dog is a genetic Carrier of prekallikrein deficiency. Prekallikrein Deficiency is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the KLKB1 gene mutation. Reliable genetic testing is important for determining breeding practices. Because affected dogs often do not have clinical disease, genetic testing should be performed before breeding. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Shih Tzu that are not carriers of the mutation have no increased risk of having affected pups.

There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.


  • Okawa T, Yanase T, Shimokawa Miyama T, Hiraoka H, Baba K, Tani K, Okuda M, Mizuno T. Prekallikrein deficiency in a dog. J Vet Med Sci. 2011 Jan; 73(1):107-11. [PubMed: 20736516]