Hi 1rovert. Flossie had part of her thyroid removed a couple of years ago and put on weight. However a few months back she started getting thin again so she had more tests which showed that her levels were up again. Unfortunately the remaining thyroid is in an awkward position and because of her age and the fact that her heart rate is very high the vet is unwilling to operate in case of complications. She is on medication and is having steroid injections to try to boost her appetite and build her up. If she gains weight and her heart rate drops we may look at a further operation. She is fine in herself and quite lively so I let her enjoy herself while she still can.
Thanks so much for your concern and I hope your cat continues to get better. 18 is a good age isn't it?