A cat that does not poop may be caused by eating too little, too dry food, not drinking enough water, indigestion, intestinal obstruction, megacolon, or lack of exercise. You can feed the cat some probiotics to promote digestion, and then Let the cat drink more water, and then observe it for two days to see if it can defecate. If the cat still cannot defecate, it is best to take the cat to the pet hospital for examination and treatment immediately.