Development of a collagen-binding activity assay as a screening test for type II von Willebrand disease in dogs

作者：Sabino EP; Erb HN; Catalfamo JL^*

来源：American Journal of Veterinary Research, 2006, 67(2): 242-249.

DOI：10.2460/ajvr.67.2.242

Objective-To develop an assay to measure canine von Willebrand factor (vWF):collagen-binding activity (CBA) to screen for type 2 von Willebrand disease (vWD) in dogs.
Sample Population-293 plasma samples submitted for analysis of canine vWF antigen (vWF:Ag) and 12 control plasma samples from dogs with inherited type 2 or 3 vWD.
Procedure-Bovine collagens were evaluated for suitability as binding substrate for vWF Assay sensitivity to depletion, proteolytic degradation, or a genetic deficiency of high-molecular-weight vWF were determined. Amounts of vWF:Ag and vWF:CBA were measured. The ratio of vWF:Ag to vWF:CBA was used to discriminate between type 1 and type 2 vWD.
Results-An assay for canine vWF activity was developed by use of mixed collagen (types I and III). When vWF:Ag was used to subtype vWD, 48% of the dogs were classified as clinically normal, 9% as indeterminate, and 43% as type I vWD. Inclusion of vWF activity resulted in reclassification of 5% of those identified as type 1 to type 2 vWD. However, vWF:CBA of the reclassified dogs was not persistently abnormal, a finding compatible with acquired type 2 vWD. Some Doberman Pinschers had lower antigen-to-activity ratios than other breeds with type 1 vWD, suggesting that Doberman Pinschers have more functional circulating vWF.
Conclusions and Clinical Relevance-Analysis of canine vWF activity should be included among the vWF-specific assays used to confirm type 2 vWD. The prevalence of inherited forms of type 2 vWD in screened dogs is lower than acquired forms that can result secondary to underlying disease.

• 出版日期2006-2