Hi, it's been a while but I didn't come back cuz too much was happening and it was confusing. Ecco definitely showed every sign of hyperthyroidism but a low T4, but I'd put that down to his being on the herbal Thyroid Support Gold prior to testing in Jan. Anyhow I continued with it, plus cut out any fishy food (hard to do with commercial stuff and still leave any choices), plus clearing huge amts of litter, being woken at 6 am (vs 7) to feed him, plus whining through day for food, seeing big fat claws, etc. etc. But there is a little news and I'd like some feedback. Vet suggested trying Royal Canin, but on researching, I wasn't impressed with it so didn't begin. However I was also going nuts not getting enough sleep, and all of above stuff, so decided to try Hill's Y/D just a few days ago. I wasn't aware you're supposed to use it 'only', with no other food, so have continued with mostly Friskies breakfast - but no more iodine laced egg yolk (only little amts, but for all I know it started the thyroid thing) - Y/D lunch (plus little other treat) and a similar supper, with e.g. bits of ham or plain hamburger treats, etc. Well, it's only been a couple of days but there has been a change in his progression - first time in months! However now I'm worried about flipping him hyPOthyroid because of the Y/D even tho' it's not 100% of his diet... so I'm not sure what to do now! Anyone else have experience with this kind of crossroads thing? Can he flip overnight with no warning even after a short time on e.g. a 60%(?) diet of Y/D or ??? Thanks to all who've read so far!