Date: 4 May 2001 09:44:08 -0500
From: conmac@cc.usu.edu
Subject: Re: factor 8

I was involved with a research project this past year to
evaluate this very problem.  There are kits available to
determine total vwF in blood.  The one which we used was
from Diagnostica Stago out of France.  This kit was
originally set up to assay human vwF, and it apears to cross
react well with canine vwF.  The real problem though is that
vwF is a mixture of multimers of the base protein.  The base
monomer will form multimers of up to 20 mers and create
molecules of well over 2 million mw.  The current literature
indicates that deficiencies in certain size ranges of the
protein may be more important than the total serum vwF. 
Thus the elisa based determination of total vwF is of
limited diagnostic utility.  We looked at vwF dog samples
using SDS-page separation of the multimers followed by
electrotransfer to nitrocellulose and immunoblotting.  The
procedure while "doable" is very labour intensive (read
expensive) and as such we have not gone forward with
developing a routine diagnostic test for this protein. 
There are a large number of references to this type of work
which can be easily found if you search using the terms:
canine; von Willebrand Factor and diagnostics.


Brian Chelack
Prairie Diagnostic Services 
Saskatoon, SK