Good question.  The big question is IS flagyl absorbed well thru the skin
(usually the skin over the ear flaps).  The answer so far is not absorbed
well.  Last week Dr Boothe (the pharmacology guru from Texas A&M) gave a
presentation about transdermal meds, etc.  Flagyl was one of the ones
that limited studies have shown not to work well this way.  She has just
recently recieved funding from the Morris Animal Foundation to test some
of the common drugs that are being used this way (including Flagyl), so
we will know more in the near future.
 
In the mean time try to give Flagyl orally and only when needed.
 
Hope that helps,
Jerry Murray, DVM
[Posted in FML issue 3756]