title: Development of a collagen-binding activity assay as a screening test for type II von Willebrand disease in dogs.
abstract: 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.
authors.affiliation: Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Elizabeth Peet
authors.initials: EP
authors.lastname: Sabino
authors.forename: Hollis N
authors.initials: HN
authors.lastname: Erb
authors.forename: James L
authors.initials: JL
authors.lastname: Catalfamo
mesh_terms: 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
chemical_list: D014841:von Willebrand Factor; D003094:Collagen