Frequently Asked Questions on Factor XI
(Compiled and sumbitted by the USKBTC Health & Genetics Committee.)
1) What is Factor XI?
Factor XI is a coagulation protein, synthesized in the liver and circulating in plasma, the fluid phase of blood. It is one of many factors critical for the formation of fibrin the glue of a blood clot. F XI is part of the intrinsic coagulation cascade just like the well known hemophilia factors and thus its deficiency can lead to bleeding.
2) How common is this deficiency in the Kerry Blue Terrier breed?
The frequency of Factor XI deficiency remains unknown. While in the past there have been difficulties to get dogs screened for this deficiency, the new DNA test has not yet been embraced by the KBT owners and breeders. Few dogs have been screened and some were screened because relatives were diagnosed with the bleeding disorder. It would be helpful to the breed to screen a random group of champion and breeding KBTs to further determine the prevalence.
3) What symptoms will the affected dog have?
Many factor XI deficient dogs remain asymptomatic just like people with this disorder. There is no risk for spontaneous bleeding but rather induced by trauma, surgery, or illness. Dogs may show signs of hemorrhagic gastroenteritis and particularly prolonged post-traumatic and surgical bleeding. They typically may not bleed until 1-3 days post-surgery. It would be helpful to know of any bleeding problems in any KBT tested in order to further define the bleeding risk.
4) How is this inherited in the Kerry Blue Terrier? What symptoms will the carrier dog have?
The mode of inheritance is still not completely understood. It was said this was a dominant trait with incomplete penetrance while it might be more a recessive trait. With dominant traits there are no carriers. With recessive disorders carriers are by definition asymptomatic. Based upon our screening results it appears that only homozygous affecteds are at risk of bleeding.
5) How can bleeding be prevented in the affected dog when surgery is necessary?
Factor XI deficient dogs may not excessively bleed at each surgery or after each trauma. However, they are at increased risk of bleeding. Therefore, the veterinary surgeon’s utmost attention to hemostasis is important. Furthermore, fresh frozen plasma or cryopoor plasma could be used in severe cases of hemorrhage or preventatively when delicate neuron or other surgery is performed and any bleeding is undesirable and difficult to control.
6) What is the accuracy of the DNA test and cost of testing for Factor XI?
The DNA test is the most accurate genetic test available and is superior to most other tests used regularly in veterinary and human medicine. However, rarely errors may occur due to misidentification of animals, lab and reporting errors – all due to human errors. The charge is $75 per dog which is supporting the screening of the subsidized and not- for-profit Josephine Deubler Genetic Disease Testing Laboratory at the University of Pennsylvania, PennGen.
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