Dropsy is a dreadful condition and a fish with this condition are pretty much beyond treatment.
I have heard of the odd fish being cured but it's way beyond most koi keepers.
The only advice I can give you is to visit Koi unleashed and see if Duncan can help. He is one of the UKs experts on Koi health and if a potential cure exists he will know. Goto http://www.koiquest.co.uk/forum/
He may well just recommend putting the Koi to sleep but it's worth asking.
Best of luck.
Alan F.
Posted on Aug 2, 2007, 6:36 PM from IP address 213.120.101.21