My 15 year old Redd has had IBD for about 7 years. He was diagnosed by biopsy (three types of inflammatory cells were present) and it affects his lower GI, so it is mostly diarrhea and not vomiting. At first he was on Prednisolone and Metronizadole (flagyl) for about 3 months and then gradually tapered off both as he improved. We also changed him from dry food to wet, grain free, novel protein food which seems to keep it pretty well in check. We have tried almost every brand of grain-free and some of the raw frozen food too, and it is trial and error to find one that works for your cat. He did really well on Natural Balance single protein wet food for a long time. (We have sinced switched to Wellness Core due to his diabetes since it is lower in carbs.) He does get occasional flare ups once or twice a year. They are treated with a short course of metronizadole (which has anti-inflammatory properties) and cerenia (to address vomiting if present). Our vet also has him on a very low dose (1/4 tab) of cerenia twice weekly as a it has possible preventative properties and has suggested Leukeran for the same if his flare-ups start to become more frequent. Our vet also suggested adding fish oil (one squirt per day) to his food as the omega 3's may be anti-inflammatories but it seemed to set off my guy's stomach so we stopped.
It is hard to give advice since IBD can be so different cat to cat due to the location of the inflammation and the type of inflammatory cells. I would definitely say switching to a grain-free, single protein, wet food would be a good first step to try to eliminate food allergy-related triggers and remove the bulk of digesting dry food. I'm glad I didn't have to deal with long-term prednisolone use but it did help when his IBD was most severe. I've heard good things about Budesonide and B12 shots but never tried either. Metronizadole works best for my guy but I will warn that it has an incredibly bitter taste and the only way I could get it into my cat was by splitting it in half, putting it in a gel capsule, and using a pill popper. There used to be a yahoo group for IBD cats but I'm not sure if it is still around. I find flare ups are more quickly resolved if I catch it early so your friend is going to have to become an expert in cat poop observation. If my cat's poop changes from "logs" to "soft-serve swirls", becomes extra smelly or more frequent than usual, I call the vet. If you let it go, you risk severe dehydration and too-rapid weight loss, both of which are very serious. One other thing that may be helpful, not as a treatment of the illness but of the symptoms, is adding additional litter boxes. IBD cats often have the suddne urge to go, poop much more frequently each day, and produce smellier poop. Our guy had daily "accidents" until we added a box on each floor of the house. More options for a clean box someplace nearby for the cat meant less poop on the bed/couch/rug for us.
Sadly my guy now has diabetes and pancreatitis which complicates things. The pancreatitis is similar to the IBD in that it is inflammatory and flare ups in one can trigger the other. And since the diabetes means he pees all the time now too, I may end up with a house full of litter boxes if we can't get this under control soon. Good luck to your friend!
