Only one canine trial on this entire site tests a probiotic against chronic, ongoing GI disease rather than a one-off bout of diarrhea: a double-blinded, placebo-controlled study of Saccharomyces boulardii in dogs with chronic enteropathy, which found improvement in clinical activity index and stool frequency over placebo. These four products all contain that strain. That's one trial, not a body of evidence, and it was a mixed group of healthy and chronic-enteropathy dogs -- read the Saccharomyces boulardii strain page before assuming it applies to a specific diagnosis like IBD.
Contains a strain -- so far, only Saccharomyces boulardii -- with a linked canine study specifically in dogs with chronic enteropathy or IBD, rather than acute/short-term diarrhea.