Lots of things can cause diarrhea in dogs, and a single bout or two is probably nothing to worry about. You may not even need to see a veterinarian. First, make sure your pet didn’t eat anything poisonous. For a day or two, avoid treats and table scraps, and limit his food intake to regular dog food. Keep him well-hydrated. Michael Lieb, Professor of Small Animal Internal Medicine at Virgina-Maryland Regional College of Veterinary Medicine, says usually nothing specific has to be done: “most cases of diarrhea in dogs get better on their own without any specific treatment.”
However, if the diarrhea becomes more frequent, if blood develops, or if vomiting occurs, Lieb says your dog needs to see a veterinarian.