I prefer a human grade one from Solgar. Its sold at Whole Foods and GNC. It really is amazing.
However, the absolute best one for dogs, hands down, is Pet Flora. It stops diarhhea, gets my dogs through stress, stops gas, stops yeast. Its a miracle. My Cavalier King Charles had diarrhea from the moment I got him for FIVE MONTHS STRAIGHT before I found Pet Flora. The moment I gave it to him - Five months of diarrhea stopped. One day later he had his first solid stool. I swear by this. I use the solgar daily and Pet Flora 1X a week b/c its pricey. If one of my poochies is a little sick, I do Pet Flora up to 2X daily instead of the Solgar. Once the symptoms resolve, I switch back to my other routine. Before and after Ella Bean's spay, I used it and she had zero tummy upset and had perfect solid stools after surgery. You can get it here:
Pet Health Care - Natural Remedies For Your Cats & Dogs
Its soooooooo much better then the one at Petsmart you are looking at. At least use a human grade one instead of that. Good luck!