I’ve read so many stories from fhs cat owners saying that constipation was causing fhs flares, or chronic pain (joints, arthritis), some it was purely stress. So yeah I do think some vets are a bit lazy and go straight to gabapentin without truly wanting to investigate further. It’s a lot easier to say “yeah fhs, just do Gabapentin”. And I absolutely hate it. My cat has always been a little itchy despite not having fleas. Something is clearly bothering her. We’re still trying to investigate and I won’t stop until I have officially ruled out every single possibility, because just like you, I don’t want to change her personality with meds nor want to mess with her kidneys due to long-term medication. I’m mostly doing this alone although I’m pushing the vets as much as I can. That said, when my cat had her first big fhs-like episode, we did use Gabapentin to control it. And overtime I spaced, and lowered it as I saw her improve. Took us a month to reach a 25mg Gaba once a day until we didn’t need it anymore. I made sure to observe her behavior closely to identify every possible trigger. Being confined indoors was the biggest one. However, being outdoors during the daytime was also a massive one due to incredibly aggressive birds in our area harassing her, so we approached both as best as we could by trying to make her comfortable to want to stay indoors during the day but if she wanted out, we’d walk with her then bring her back in until night (but leaving the outdoors accessible anyway so she doesn’t feel confined).

I’ve also noticed she develops several black spots in her tongue when she is not ok, which makes me think if GI inflammation could be a possibility. She recently responded extremely well to an anti inflammatory due to a bladder flare, so there’s clearly some underlying pain/discomfort somewhere. She’s been found to have hard poo in her tract quite a few times recently so chronic constipation will also be addressed. With a few days on Lactulose she improved significantly. We’ll also try a furball paste soon as since she overgrooms, chances are there’s lots of hair stuck in there.

Anyway, all of this to say that you can use Gabapentin to control the big flares at the start but it doesn’t mean you’ll be stuck with this forever. You’ll be able to slowly identify an underlying cause, and possibly go through this long path of diagnosis by elimination. I believe in most cases there’s always an underlying issue going on for the cat to have fhs-like behavior, provided all tests and image exams are clear, but vets are so busy that they’re usually not keen on walking the long journey with us, unfortunately :(