If you live in any location in which there are mosquitos, you should be
treating your ferrets for heartworm.  Ferrets in Florida should be treated
12 months out of the year.  Other parts of the United States can treat
heartworms seasonally -- the times of the year that mosquitos can live;
typically spring, summer, and fall.
 
One single mosquito bite can give your ferret heartworm.  A cure is
unlikely.  Prevention is they key!  I live in the Tampa area and treat my
ferrets monthly with a liquid concoction of ivermectin, ferretone, and
propylene glycol.  This is mixed and prescribed by Dr. Deborah Kemmerer at
the West End Animal Hospital in Newberry.  Dr. K's web site is
http://www.atlantic.net/~weah/ and she has some information in the Ferret
FAQ about heartworms and heartworm tests.
 
I just lost my Tigger to a heartworm. She apparently already had the
heartworm when I rescued her. When you give your ferret heartworm
medication, it will NOT kill any existing heartworms; just prevent new
ones from growing. Tigger was a healthy, happy 3-year old who needed
routine adrenal surgery. Although the surgery was successful, she died
the next day. The necropsy showed a heartworm; Tigger's heart could not
take both a heartworm and surgery at the same time. We are heartbroken,
but relieved that our other nine ferrets tested negative for heartworms,
and we religiously give monthly medication to them all.
 
- Erika and the Tempestuous Ten
[Posted in FML issue 2677]