Genetic Test for Glanzmann’s Thrombasthenia in Great Pyrenees and Otterhounds

Glanzmann’s thrombasthenia (GT) and Thrombasthenic thrombopathia are bleeding disorders that are caused by a defect in platelets and are found in Great Pyrenees and Otterhounds, respectively. In 1967 Otterhounds were diagnosed as having Thrombasthenic thrombopathia.1 Through identification of the disease and responsible breeding practices, it was believed that Thrombasthenic thrombopathia was eliminated from Otterhounds. Unfortunately, it resurfaced in the 1990s in descendents of the originally diagnosed Otterhounds. At the same time, Great Pyrenees were diagnosed with GT.2 Research performed during the late 1990’s and early 2000’s showed that these two conditions, which closely resembled each other, were caused by genetic mutations is the same gene which resulted in a defect in platelets.2-4

Platelets are the blood cells responsible for blood clotting.  When there is injury to blood vessels, platelets coagulate, ie stick together, and bind to the opening in the vessel. The platelets in Great Pyrenees with GT have a genetic mutation in glycoprotein complex IIb–IIIa, components of coagulation.3  Similarly, platelets in Otterhounds with Thrombasthenic thrombopathia have a genetic mutation in only glycoprotein IIb.4 Thus, these affected dogs have platelets less able to adhere to each other and to the tissue of the damaged blood vessel resulting in excessive bleeding. Because of this defect in the ability to stop bleeding, these dogs are more likely to have nose bleeds, bleeding gums, and excessive bleeding caused by minor cuts and scrapes. These two conditions are now clinically considered to be the same, GT.

GT is a condition seen very early in the dog’s life. Young dogs are prone to spontaneous bleeding. Even though it is easy to detect that the dog has a problem at an early age, it has not been easy to diagnose the problem. Until recently, extensive biochemical tests needed to be performed to determine if GT was the cause of the bleeding. But now, a genetic test is available. Not only will the genetic test effectively diagnose those dogs with GT, it is also able to determine the carriers of this autosomal recessive disease which do not show any signs of the condition. This provides breeders with the knowledge to breed responsibility by simply submitting a blood sample to have a genetic test performed.

For more information about Glanzmann’s thrombasthenia genetic test for Great Pyrenees and Otterhound, contact Mary Boudreaux, DVM, PhD from Auburn University at (334) 844-2692 or email boudrmk@vetmed.auburn.edu. You may also visit the following websites:

http://www.vetmed.auburn.edu/uploads/images/3930/GreatPyrWebInfo.pdf

http://www.vetmed.auburn.edu/uploads/images/3934OtterhoundWebInfo.pdf

References

1. Dodds WJ. Familial canine thrombocytopathy. Thromb Diath Haemorrh Suppl 26:241-248, 1967.

2. Boudreaux MK, Kvam K, Dillon AR, Bourne C, Scott M, Schwartz KA, Toivio-Kinnucan M. Type I Glanzmann’s Thrombasthenia in a Great Pyrenees Dog. Veterinary Pathology 33:503-511, 1996.

3. Lipscomb DL, Bourne C, Boudreaux MK: Two genetic defects in alpha IIb are associated with Type I GT in a Great Pyrenees dog: a 14-base insertion in exon 13 and a splicing defect of intron 13. Veterinary Pathology 37:581-588, 2000.

4. Boudreaux MK and Catalfamo JL. Molecular and genetic basis for thrombasthenic thrombopathia in Otterhounds. Am J Vet Res 62(11):1797-1804, 2001.