Hello,
I think that if your cat isn’t responding as expected that it’s time to go back to the vet. I also think that you should talk about al of the other possible causes to his current clinical signs. A polyp is on the list of possible causes.
Good luck.
Hello,
It sounds like you have done a pretty thorough work up. The places I think that you should look into are;
Repeat the blood work. It sounds like hyperthyroidism. I always check a free T4 on top of the thyroid T4. I also check a urine. If you haven’t sent a fecal to the lab too.
After that the ultrasound and X-rays are where I look.
You are still at the place where the diagnosis is eluding you. That’s where you need to focus.
PS. Just for the record I don’t love starting pred until you have a diagnosis. It can obscure your diagnostics.
Good luck. I hope this helps.