Nicholas, you need to treat the root cause of the ascites. Usually it
is cardiac disease for ferrets, though it can be cause by some other
things, so the first step is chest x-rays.

You can read about cardiomyopathy and a range of other health problems
in http://ferrethealth.org/archive/

which is very easily used.

Sukie (not a vet)

Recommended ferret health links:
http://pets.groups.yahoo.com/group/ferrethealth/
http://ferrethealth.org/archive/
http://www.afip.org/ferrets/index.html
http://www.miamiferret.org/fhc/
http://www.ferretcongress.org/
http://www.trifl.org/index.shtml
http://homepage.mac.com/sukie/sukiesferretlinks.html

[Posted in FML 6007]