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


METHODS
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.


METHODS
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 1 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
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.
Sabino
Elizabeth Peet
EP
Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Erb
Hollis N
HN
Catalfamo
James L
JL
D000818:Animals; D003094:Collagen / Q000378:metabolism*; D004283:Dog Diseases / Q000097:blood / Q000175:diagnosis* / Q000378:metabolism; D004285:Dogs; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D008297:Male; D012680:Sensitivity and Specificity; D014842:von Willebrand Diseases / Q000097:blood / Q000175:diagnosis / Q000378:metabolism / Q000662:veterinary*; D014841:von Willebrand Factor / Q000032:analysis* / Q000378:metabolism
D014841:von Willebrand Factor; D003094:Collagen