Hyperthyroid cat on Felimazole gel not eating

[drosophilavirilis]

I have a 12 year old female cat that started having GI issues this April. Started with foul smelling diarrhea (old drain/sewage smell, not even poop!), then vomiting, then she wouldn't eat for several days. Naturally I took her to the vet where she had an X-ray and a full blood panel done, where they found out she has hyperthyroidism. She got a bit of IV drip (well, I guess for cats it's not really intravenous, so subcutaneous drip?), some anti nausea pills and Felimazole pills.

The first week was fine, she took her pills happily enough with the help of a maleable treat. Then she vomited one day and refused to take the treat again. Since then, it's been a nightmare. We've been going to the vet basically every week. She repeatedly gets better, then worse again. It's always the same, she'll get her appetite back, eat like a maniac for a few days and look better, then vomit and go off food for a while. Forcibly pilling her made it worse, so I took her off the tablets. I organized a radioiodine treatment in July (will have to go abroad), but I can't take her there unless she's stable. She's down to 2.9kg from her normal 4.5kg.

During our latest vet visit they started suspecting a bacterial infection as well, due to high leukocyte counts in her blood. She got an antibiotic shot and miraculously she was her old self in a day. That seemed to make sense, since the issues started when I put her on some store-bought raw food (been making my own for years, only thing that fixed her diarrhea long ago) and I suspect it was contaminated. I got really happy for a bit, hoping she'd get in shape to go to treatment, then a few days after the antibiotic the symptoms came back all over again.

Pilling her with Felimazole is impossible, and she vomits it back out immediately, so I somehow managed to get my hands on some Felimazole gel (can't get it in the EU, had to get it from Switzerland for a small fortune). She's been on that for a few days now and she seems even worse. Hiding, hardly eating, vomited once... I'm thinking maybe the antibiotic wasn't enough and the infection came back. Her poop is solid, but still smells like a rotten drain more than feces.

I just don't know what to do anymore. Vet doesn't seem to know either. I guess I'm asking if anyone had a similar experience and if there's any chance for a good ending. Is there any chance this is all the hyperthyroidism and Felimazole side effects and she'll get better after the side effects "wear off"? I just need her to get stable enough to get her treatment, but I don't even know if the hyperthyroidism is all that's wrong with her... Any past experiences appreciated.

[Mollycat]

Have you considered the Hills y/d diet instead Felimazole?

Whereabouts are you in the EU with no radioiodine centres?

Oh and by any chance was her bilirubin high in the full blood panel?

[drosophilavirilis]

I got the y/d food from my vet, but she won't eat it. She's been extremely picky since the issues started, so I literally buy one of each type of wet food I can find and offer them one by one until she eats something. Often it's the lowest quality one, but I'm just glad she gets some calories. I'll see if I can get her to eat the y/d food when/if she gets her appetite back again, but of course I don't want to mix treatments.

I do have an appointment for iodine treatment on the 25th if this month in Vienna (live in Slovenia), which is about a 4h drive. I'm more worried that she's in no condition to survive the trip and treatment...

Last blood check was last week, just before I started the Felimazole. I didn't see it myself but the vet went over everything and besides T4 being high, slightly elevated creatinine (which he attributed to muscle loss) and high leukocytes he said there's nothing out of the ordinary.

I'm still thinking there might be some sort of pathogen in her gut. The poop smell is really something...

[Mollycat]

The reason I ask is because my girl had some kind of crash and the tests were how we discovered her hyperthyroidism, she was if anything overweight and not especially desperately hungry, but the crash was vile stinky diarrhoea, often yellow or orange in colour, and then a frightening weight loss. It was something to do with her liver, possibly pancreas, and bilirubin which if it's not the case with your cat I won't bore you with all the details - but it doesn't have to be pathogens in the digestive tract to produce those symptoms, it can be issues in the liver and pancreas. We focused on HT and said we'd talk liver later. She's fine.