Saccharomyces boulardii is a probiotic yeast, not a bacterium -- the distinction matters because antibiotics that kill bacteria don't touch it, which is why it comes up often in "what to give during antibiotics" discussions. It's sold both as a dog-labeled supplement and, off-label, as the human probiotic NOW Saccharomyces Boulardii. Some labels print a registered strain code (CNCM I-3799); many just print the bare species name.
PubMed and PMC, dogs only. Other species are listed separately below and don't count toward the badge.
We don't have a confirmed CFU-per-kg dose number for Saccharomyces boulardii from the canine trials yet (Exact CFU dose not recoverable from the retrieved abstract of the one canine trial (D'Angelo 2018, PMID 29212912) -- needs a full-text check before quoting a number on-site.) -- so this calculator is intentionally disabled rather than guessing.
Owners do, and it's the same species, but it isn't labeled for dogs, so there's no label dose to follow -- any dosing would come from the one canine trial we found, not from the bottle.
Being a yeast, it isn't killed by antibiotics that target bacteria the way bacterial probiotics can be -- but we found no canine trial testing it specifically for preventing antibiotic-associated diarrhea, despite that being a well-studied question in humans. Don't assume a dog study exists just because the human one does.
We found no dog case reports, but in severely immunocompromised human patients -- chemotherapy, central IV lines -- S. boulardii has rarely caused bloodstream yeast infections. Ask your vet before use in an immunocompromised or catheterized dog.