Ninj was hyper thyroid, he didnt have the therapy as I think it would have been to hard on him to put him through it - he would have had to stay in hospital along with his other complications and he had never had any vaccinations meant it wasn't really feasible especially when they couldn't guarantee he would improve for having it done (the perils of being a stray and not knowing his age or history). I struggled to get him to take pills as he would eat around them, if he ate at all. In the end it was kinder to let him go.
HOWEVER, there is an Transdermal methimazole gel that you can use if he doesn't mind having his ears fussed
All you do is put the right dosage onto your finger (gloved!) or a cotton wool pad and rub it on the inside of the ear. It's very easy to do as long as your cat is used to being fussed round the ears.
https://www.youtube.com/watch?v=xq0vmoi-GwI (about 7 and a half minutes in!)
and
https://www.youtube.com/watch?v=rQG6MC99ItkIt was never very effective for Ninj but he didn't like having is ears fussed so I did find it difficult to ensure he got the full dose - with Robbie and Sky it would be easier as they are used to it.