Dear Sandra:
 
>I have a question regarding doing a snap test for a heartworm check in a
>ferret--if a ferret can harbor only one or two adult worms, what if they
>happen to be male worms?  I understand that a snap test only indicates if
>an adult female is the culprit; apparently it detects the hormones put
>out by a female?
 
WHile I am not an expert in the occult heartworm test, I believe that the
antigen that is used is a saline extract of whole female worms, not a
hormone that they put out.  This means that the test looks for sustances
that would be part of the body of the worm, and should be present in both
sexes.  As such, I think that even exclusively male infections should be
picked up by the test.
 
>Was reading an article in a vet magazine tonight regarding detecting
>heartworms in cats, and the article said that a lot of cats only harbor
>male worms (for whatever reason), that the snap test is designed for dogs,
>and even if the cat does have a significant load, the snap test may not
>pick the presence up.  They recommend ultrasound.  Would this be the
>prudent choice for detection in ferrets, rather than using the possibly
>useless (in ferrets--works great in dogs) snap test?
 
Ultrasound may be useful, but is probably not cost-effective.  Not many
practices actually have ultrasound equipment, and many rely on other vets
who come in on an as-needed basis to read ultrasounds.  Dr. Debra Kemmer
reports several cases in which ultrasound by experienced specialists wither
falsely identified or failed to identify heartworm, while the Snap tests
has performed more reliably with a lesser number of false negatives.  False
positives should also not be a problem with the SNAP test.
 
I know that Dr. Kemmerer does lurk around here - perhaps when she gets a
chance she can expand on her experience a bit - as probably the nation's
expert on heartworms in ferrets.....
 
With kindest regards,
Bruce Williams, dVM
[Posted in FML issue 3233]