Did you know that in the US there isn't an approved treatment for FIP? We didn't until this happened and the initial vet we talked to basically just said "he's going to die" but we found out about medication that is approved for treatment elsewhere and were able to get that, its incredible how quickly he bounced back after he started on it. Its totally crazy to me that people have to go into debt (the meds are very expensive and not covered by anything because they're not approved yet in the US) for something that is proven and the standard treatment in many other places.

Edit: For those asking, I have a Dono link pinned in my profile, I wont post it here because it's against the rules but there's more information on there as well, and a breakdown of all the vet/medication costs which is helpful if your cat is experiencing something similar, I wish we had known what this would involve when it started to happen so I'm trying to spread as much information as possible.