Hi Andrea,
For my dog with GI issues it was a combination of evaluation by the internist and trial and error food trials.
Between the tests at the regular vet and the ultrasound by the internist many causes were ruled out. Intestinal disease was suspected as the root cause based on the ultrasound findings but there were some pancreas changes as well.
The internist at this point recommended food trials over biopsy, at first eliminating all treats and using limited ingredient OTC foods. I did a trial with California Naturals chicken and rice and later lamb and rice. I kept a journal of symptoms as GI symptoms can wax and wane and we wanted to track in a more objective manner. I don’t remember how long I had him on each diet before changing I think about 6 weeks. The first two changes, no difference was found. Next we went to a vet therapeutic limited ingredient food and signs then resolved.
If I were to do it again I probably would approach a trial like I would for food “allergy” meaning taking an inventory of everything he had been exposed to and then taking in consideration common cross reactions choose a veterinary therapeutic diet for the trial.
I’m not a fan of using a hydrolyzed version of an ingredient the dog has been exposed to but I know of several dogs now with G problems that have done very well on hydrolyzed diets of an ingredient novel to them.
