I have a shih tzu who weighs 11 pounds. Last Wednesday he became ill, we called the vet and they weren't too worried. On Friday he started having bloody diarrhea so we called and took him in. They put him on medication to stop the diarrhea but he hasn't pooped since then. We called today and they don't seem too worried but I am! he's got eight meals in him and Im worried if I keep feeding him, it'll hurt his stomach or something. He usually goes once a day so it's very unusual he wouldn't go for four whole days. Other than that, he's starting to feel better. He was pretty down for a while b he's starting to perk up now.