Thanks for the follow-up.
Norway is a very old girl. You’ve done well to get her to such an age. She’s also very lucky to have an owner who is so caring.
Hyperthyroidism is a common problem in old cats and thiamazole is the standard treatment. It usually works well. Unfortunately it’s not a very palatable drug…cats hate the taste. In addition to that hyperthyroid cats can be a bit grumpy and difficult to dose. If she’s not getting the medication she will continue to deteriorate. If you can somehow force the medication into her then you may see her appetite return. Most vets carry a special dosing instrument called a Pill Popper. This is a plastic tube with a soft latex tip that allows you to safely (for cat and owner) deposit a pill at the back of the throat. Ask your vet about that.
At her age we will usually expect to see some degree of kidney problem too…chronic renal failure (CRF). From what you say she was okay in that way but things can change quickly. It may be that her kidneys are starting to cause problems. A repeat of the kidney function test may be worthwhile.
Tangling of the coat is common in unwell aged cats because they stop grooming themselves. You must take over this task with a steel comb. If the coat is left like that she could develop skin irritation or infections.
“Retracted eyes” could signal dehydration. If she is only taking small amounts of water then that may be the case. You need to encourage her to drink until you see your vet. He/she can determine if she’s dehydrated and can give her fluids by i/v drip or subcutaneously if necessary. In the meantime try using a turkey baster to trickle water into the side of her mouth.
Unfortunately from what you’ve described this does not sound like a very hopeful situation. It may well be that the rest of her system is starting to decline and once this happens it can progress rapidly. Rehydration can sometimes give us a quick response but unfortunately it is not always sustained. You need to have her re-assessed by your vet soon. It may be that her time is coming. This is a difficult thing for me to discuss with you because I don’t know what are your feelings about euthanasia. But you must consider the quality of her life. If there is no quality then it may be better that she gently goes to sleep. There is no reason to feel guilty if that is your decision. She has had a good long life with a loving owner and you have, I’m sure always made the best decisions for her. That “final decision” is perhaps the most important one we ever make for our pets.
I hope I’ve been of help. Please contact me back if I can assist further.
Good luck. Kindest regards, Peter