I had two boys with HT. Both were managed with felimazole, Jake for 2 years, Bailey for 4 years. I lost Jake to kidney disease and bailey to heart failure.
First, the tablets….oh, I feel for you. Bailey was a bit hit and miss but we found Good Girl catnip drops on amazon and they were a life saver. They’re soft so you can mould them round the tablet. Worked a treat for both of them.
Jake eventually became a nightmare with tablets and eventually we had to move to the ear gel Mark mentioned. My vet hadn’t heard of it at the time but he ordered it for me. It was no problem to give Jake and he was on it for the last year of his life.
I considered surgery, but as others have said, it’s not a cure. Then we looked into radioiodine but due to my cats having other health issues we couldn’t do either of those options.
The tablets work well and the HyperT is manageable on them, unfortunately, the tumour keeps growing so over time the dose needs increased. Bailey was on 6 tablets a day in the end. I got very good at spotting the symptoms of it going up again even without his blood tests!
Your cat will need regular blood tests to make sure the T4 is under control for the rest of her life but if she gets the right dosage and you and your vet keep on top of it, she will be fine.
One thing is to make sure your vet keeps an eye on her kidney function. HyperT can mask kidney failure, so it’s vital that her kidneys are tested once she’s stable too.
Good luck, I hope you find a solution to the pill problem!