I really don't know anything about pancreatitis, but do know a bit about bowel issues.
Does Tus have diarrhea or constipation? Any mucous or blood on her feces?
As for pred, I know it is a dreaded drug for humans. It makes them feel horribly moody, and ill along with weight gain. Some would rather have their colons taken out than to be on pred for the rest of their lives to control their disease. Others don't do too bad on it. Now I can't speak for cats, and as far as I am concerned, neither can vets as cats can't speak to them.
Cat maid to:
Jasper, male Ragdoll ?? (approx 10 yrs)
Rose semi feral, a cpietra rescue, female tabby (approx 7 yrs)
Sweet Pea RIP (2004?-2014)
Puddles RIP (1996-2014)
Snowball RIP (1991-2005)
In a cat's eye, all things belong to cats.-English Proverb
“While we are free to choose our actions, we are not free to choose the consequences of our actions.” Stephen R. Covey