@MaxBooBooBear:
For Max, he was referred to a specialist who did a GI series on him. He was give barium, and then they Xrayed him all day as it went through his system. I believe this ruled out other things and they ended up with a "tentative" diagnosis of mild IBD.
Also they can do thinks like a biopsy of the stomach lining and also they now do Endoscopic procedures which many times will show more then a barium xray… certainly did with me... when they could not find my ulcers... and they use the endoscopy procedure to do the biopsy also.
And not to say the he might not have an ulcer.... again, you need a referral to a specialist. IBD is not uncommon to Basenjis or many dogs for that matter.