Von Willebrand disease in Norwich terriers

Von Willebrand disease (vWD) is an inherited bleeding (coagulation) disorder. vWD exists in Norwich terriers, as is documented here. More information about vWD in dogs is available in the 1984 article ([1]) by Jean Dodds, or this Cornell web page.

Affected Dog

"Shaksper Bianca Minola" (Bianca), is a female Norwich terrier, born in 2001 ([2]). In 2003, after prolonged bleeding time from a nail cut, a von Willebrands assay was performed and gave a postive result - low von Willebrands factor ([3]).

Further Testing

Because a von Willebrands assay has a high rate of false positives, the test was repeated with different vets doing the blood draw and different labs performing the assay. The results ([4], [5], [6]) confirmed a diagnosis of von Willebrands disease (vWD). Because thyroid disease can cause low von Willebrands factor a thyroid panel was run at Michigan State University and was normal [7]. A repeated thyroid test done in 2009 also reported normal [8].

von Willedbrands disease is divided into three types:

    vWD Type I     decreased vWD factor
    vWD Type II     normal vWD factor but abnormal multimers
    vWD Type III     absence of vWD factor

The coagulation study of [6] ruled out Type II in Bianca. (Type II is commonly found in Collies, Chinese Cresteds, and Pointers.) Since Bianca has some von Willebrands factor, this rules out Type III (a deadly form of vWD found in Shelties and Scotties). This means that the type of vWD in Norwich terriers is most likely Type I, which is commonly seen in Bernese Mountain Dogs, Pinchers, Kerry Blue Terriers, Manchester Terriers, Papillions, Pembroke Welsh Corgies, and Poodles.

DNA testing

In 2003, VetGen [9] tested Bianca's DNA using their available and in research vWD DNA tests. None indicated vWD ([10]). In 2011, the tests were repeated using their vWD Type I and Type II DNA tests. Again the tests did not indicate a carrier or affected status ([11]).

Discussion

The most likely explanation is that Norwich terriers have a vWD type I mutation different than the mutation found by the VetGen vWD Type I DNA test.

Blood DNA sample

Bianca was never bred. A blood DNA sample from Bianca was deposited in the CHIC DNA repository ([12]).

References

[1] Von Willebrand's Disease in Dogs, WJ Dodds, Mod Vet Pract. 1984 Sep;65(9):681-6.

[2] Shaksper Bianca Minola, AKC registration number RM34138201, born 20010502.

[3] Lab Report page 1, page 2, Feb 2003, Antech Diagnostics, Dr. Cox did blood draw, Von Willebrands assay of 48 with normal being 70-180.

[4] Lab report, Mar 2003, Antech Diagnostics, Dr. Volk did blood draw, Von Willebrands assay of 36 with normal being 70-180.

[5] Lab report, Jul 2003, Cornell University, Dr. Johnson did blood draw, vWF:Ag=50 measured in an ELISA (normal 70-180, borderline 50-69, carrier 1-49).

[6] Lab report, Aug 2003, Cornell University, Dr. Shaw did blood draw, vWF:Ag=29 (von Willebrand factor antigen; plasma von Willebran factor concentraion, ELISA method, normal 70-180); vWF:CBA=31 (von Willebrand factor collagen binding assay, ELISA based functional assay), Ag/CBA=1 (ratio of vWF concentration to vWF collagen binding).

[7] Lab report, Mar 2003, Michigan State University Animal Health Diagnostic Laboratory.

[8] Orthopedic Foundation for Animals, Aug 2009, NT-TH12/99F-VPI.

[9] Vetgen LLC, VetGen web page on von Willebrand disease

[10] Email from Cheryl Hogue, VetGen Research Coordinator, 10 June 2003.

[11] Email from Ann Arnold, VetGen Office Manager, 21 March 2011.

[12] Canine Health Information Center, Feb 2011, NT-DNA-24B