Shih Tzu Prekallikrein Deficiency DNA Testing Guide

The Shih Tzu is one of the most popular dog breeds in the UK, ranking eighth out of 244 breeds. These small, affectionate dogs belong to the Kennel Club’s utility group, a classification that surprises many who expect them to be toy dogs.

Originally bred for work, Shih Tzus today are beloved companion animals known for their loving nature and strong bonds with owners. They thrive on companionship and attention, and while they do require some exercise, their needs are modest, making them ideal lapdogs for those seeking a quiet, small breed to share a lot of time with.

Thanks to a large and diverse gene pool in the UK, Shih Tzus generally have fewer hereditary health problems than many pedigree breeds. Still, like most purebreds, there are inherited conditions present, including one called prekallikrein deficiency, also known as Fletcher factor deficiency. This rare hereditary bleeding disorder has notable implications for affected dogs, influencing their care and lifespan.

What is Shih Tzu Prekallikrein Deficiency or Fletcher Factor Deficiency?

Prekallikrein deficiency is a genetic bleeding disorder caused by a mutation in the KLKB1 gene. It affects the essential early stages of blood clotting, resulting in prolonged bleeding after injuries or surgery. While some dogs may have mild symptoms, this condition can cause excessive bleeding even from minor trauma and increases the risk of internal bleeding, such as in the gastrointestinal tract.

This condition is rare and, as of 2025, has been identified only in Shih Tzus, making breed-specific awareness and testing especially important.

How is Prekallikrein Deficiency Inherited in Shih Tzus?

The disorder follows an autosomal recessive inheritance pattern, meaning a dog must inherit two copies of the mutated gene (one from each parent) to be affected. Dogs with only one copy are carriers, showing no symptoms but able to pass the gene to their puppies.

Understanding the genetic status of parent dogs is vital to assess the likelihood of affected puppies:

• Two clear parents will have clear offspring.
• Two affected parents will have all affected offspring.
• Two carrier parents have a 25% chance of affected, 50% carriers, and 25% clear pups.
• Affected mated to clear results in all carrier pups.
• Carrier mated to clear results in 50% carriers and 50% clear pups.

DNA Testing for Prekallikrein Deficiency

If you plan to breed your Shih Tzu, DNA testing is a crucial step to ensure healthy puppies. Your vet can collect a blood sample or buccal swab and send it to an approved UK laboratory that tests for this condition. The results classify each dog as clear, carrier, or affected.

This knowledge helps breeders make informed mating decisions, avoiding breeding two carriers or affected dogs together, thereby reducing the risk of affected puppies. It is a responsible breeding practice aiding long-term breed health.

Managing Dogs with Prekallikrein Deficiency

While there is no cure for prekallikrein deficiency, awareness allows for special care. Avoiding unnecessary surgeries where possible, preparing for potential bleeding complications, and ensuring any injury is promptly treated by a vet are important measures for affected dogs.

Early diagnosis through testing and cautious breeding significantly help reduce the incidence of this condition in the Shih Tzu population.

Why Responsible Breeding Matters

Maintaining the health and wellbeing of Shih Tzus depends largely on responsible breeders who utilise genetic testing and follow best practices. Screening for hereditary conditions like prekallikrein deficiency is part of ethical breeding that prioritises the welfare of future generations over short-term gains.

Always seek out reputable Shih Tzu breeders who conduct health testing and are transparent about their breeding practices. This benefits not only your prospective puppy but the entire breed community.

Conclusion

Prekallikrein deficiency is a rare but impactful hereditary bleeding disorder uniquely affecting Shih Tzus. Thanks to modern DNA testing, breeders can now identify carriers and affected dogs and make informed choices to prevent passing this condition to puppies.

If you own a Shih Tzu or are considering breeding, discussing genetic testing with your vet is a responsible and caring step. This helps safeguard the health of your dog and supports the broader breed health, ensuring many joyful years of companionship.

By embracing genetic knowledge and responsible breeding, we can protect the beloved Shih Tzu breed from this bleeding disorder and promote happier, healthier pets for UK families.