Rescue Remedy (also called Kennel Drops) calms down cats and dogs.

There is also something called Feliway. My older cat is on it for life - he used to be wild, loved being an indoor cat, took to a new cat well, but my vet says that stress caused his urinary infection. There were only a few crystals, but lots of infection. So he is on this to take the stress effects away. It was this or tranquilizers - more cats are on them than you think - and I am glad I got to use the Feliway.

I think Rescue Remedy is available at pet stores. You just put it in Ducky's water. Maybe just make a phone call to your vet, and get advice on it from the tech or the vet.

Good luck!