A dog shivering for no reason may be caused by cold, fear, excitement, discomfort, food poisoning, or epilepsy. If the dog often suffers from this condition, you need to take the dog to the pet hospital for examination to avoid delaying the condition. Pay attention to keeping your dog warm, especially puppies and short-haired dogs. Try not to let the dog sleep directly on the ground. You can prepare a kennel and blanket for the dog.