Need Advice! Great Dane/Mastiff with bad diarrhea My brother has a 3 year old Great Dane / Mastiff mix that weighs 192 pounds. For the past 12 or so hours, he has had very bad diarrhea. It is basically liquid and is a bright yellow color. Does this sound fairly normal for an upset stomach or should he be concerned? If it lasts for any amount of time, he will be brought to the vet, but in the meantime, I am hoping that someone can offer advice to help my brother and my parents get through the night with the sick dog. I have heard that canned pumpkin or Pepto-Bismol can soothe a dog’s stomach, but I would have no idea about the amount/dosage to give a 192 pound dog. Any advice would be appreciated!