It is normal for a dog not to poop for one day. It may be that the dog has eaten less on this day, so there is no defecation. If the dog does not poop for 2 to 3 days, it is constipated. You can feed the dog some Probiotics can promote gastrointestinal motility and let the dog eat some light and easy-to-digest food. If it still doesn’t poop, it is best to take the dog to the pet hospital for examination to avoid delaying the condition.