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>I've always read that ADV testing should be done after 12 weeks of age.
>You are saying that weaning time is of importance.  Can you point me to
>the references for this?  I do try to test but I'm becoming more of a
>skeptic about it since it seems that no matter how we test, or when we
>test, it's not correct or there are problems with the tests.
>
>Is the later testing for ADV perhaps because the ADV tests aren't able
>to factor out residual antibodies that might be in the blood?
 
Okay, folks - this may have been answered, but since I'm on digest, I
don't always get the posts in a timely manner.
 
This confused me as well, quite honestly, so I called and spoke to
the people at United.  They said quite firmly that their test is not
considered to be an accurate *negative* until the ferret is at least
four months of age and preferably six months *if* the mother was positive
or of unknown status.  The reason for this is that if the mother is
positive, the kit will not recognize the virus as foreign until the kit's
immune system has developed fully (see Dr. Williams wonderful discussion
of immune systems earlier).  Therefore the kit will not produce
antibodies against the virus until the immune system is developed and
that is considered to occur - in MINK - at six months of age.  There have
been no studies done at this time on when ferret systems are fully mature
that I (or United) is aware of.
 
A kit from a known negative mother, of course, will not have that problem
and a negative test can be trusted in that event.  So my twelve week old
privately bred boy can be tested with confidence, but my sixteen week old
pet store boy cannot.
 
A positive is a positive, regardless of age - as long as the kit is over
twelve weeks old so that any of the maternal antibodies are gone!  - but
can be a false positive, of course.  It has nothing to do with weaning
time - it has to do with the amount of antibody passed in the colostrum
in that crucial 24 hour period after birth.  The more antibody passed,
the longer it takes to go away, but we have confidence that it's gone at
twelve weeks.
 
Now this holds true for United's test - I don't know about Avecon's.
 
Dr. Ruth
*****************************************
Save lives - spay or neuter your pet.
[Posted in FML issue 3920]