IV fluids and bypassing the digestive system entirely?

Did they indicate where the inflammation was found (e.g. large or small intestine)? IBD can be caused by many things, such as food allergies, food malabsorption, Cushings disease, parasites including protozoan infections. Or it may be true IBD where local inflammation causes problems in the intestines.

Presumably they have ruled out pancreatitis, or enzyme deficiency?

If they are not giving IV fluids, I'd be asking WHY! I would ask if they could start the dog on Zofran (potent anti-nausea drug and expensive), and metronidazole (prevents bacterial and protozoan overgrowth, and is a mild anti-inflammatory), along with an acid blocker (high doses of Prednisone will induce ulcers via acid irritation in the stomach), in addition to Prednisone.

If it's true IBD then long term use of acid blockers and metronidazole (or sulfasalazine and tylosin) in addition to a low fat, easily digestible fiber diet (Hills i/d) will help keep things under control. But make sure it's not an enzyme/pancreas problem before covering up the symtoms long term.