Our vet made up a liquid suspension of Ivomec 1% in propylene glycol.
She got the recipe from Ferrets, Rabbits, and Rodents (the pink book)
which discussed heartworm in ferrets on pgs 69-70.  This medication needs
to be stored in the dark and has a 2 year shelf life.  We give ferrets .2cc
per kg of their weight once a month.  And the ferrets don't even fight
taking it.
 
Not all heartworm pills are created equal.  The medicine in some is not
evenly distributed throughout.  Also, if you are using a pill that you have
to quarter or halve or whatever, the book warns to discard the remaining
pill as efficacy lessens once pill is broken.
 
Dr. Kemmerer also has an excellent article with pictures (and they aren't
pretty) at http://www.miamiferret.org/fhc/heartworm.htm
 
-Lo
not a vet
[Posted in FML issue 2985]