It’s no difficult to find answer if you can access Internet. Just search with your required question. But let me tell you something. It all depends on the state of the animal and what animal it is. Smaller animals have faster heartbeats. The reason smaller animals have such as fast heart rate is for several reasons: Smaller animals are constantly on the lookout for danger and must be able to react quickly when they need to. A fast heart and breathing rate ensures that enough oxygen is being put into the bloodstream to allow the animal to move quickly without getting tired, or eaten. Also, because the animal is smaller, it doesn't take the blood very long to travel one loop around the circulatory system, as it might if it were an elephant or a whale. The circulation is therefore quicker allowing the heart less time to relax in between pumps.