Usually high fat diet or indulgence (like my DD's roommate was feeding her Schip bacon every morning and my DD didn't know it.....) but as Jennifer said, I think some of it can be stress.
I had good success with Solid Gold Holistique Blendz and Shadow did go thru a life threatening bout of pancreatitis when he was on it! It happened once for him. There are two schools of thought regarding antibiotics. With him, we did it all--two kinds of antibiotics, fluids and nothing by mouth for 3 days and acupuncture. Almost lost him and I have no doubt acupuncture pulled him through.
Jodie had a bad bout of it when I first got her. After that time, she had mini bouts and pulled through without vet treatment. I would keep in contact with them and as long as she was drinking and not vomiting, etc., I kept her at home. They would last a day or two of not eating and she would bounce back.
A good senior kibble low in fat should help. Also, no chicken! I know a Dobe that would go into pancreatitis after eating chicken every time. I don't know why, but I wonder if there is an allergy connection somehow. I simply kept chicken out of the diet of anyone I knew was prone to pancreatitis.