Yes, dog do have a belly button, but most canine belly buttons are not readily visible.
The main reason for many people thinking that dogs do not have a belly button is that canine belly buttons are very different from those of humans. While human belly buttons are easily visible, canine belly buttons are often nothing more than a vague scar.
They do not look like a hole in the stomach. Consider a dog’s belly button, which is also known as the umbilicus. This is where the blood vessels from the placenta attach to the puppy before it is born. These blood vessels are important to life because they provide nutrition and help with oxygen and waste product removal. Once a puppy is born, it no longer depends on the blood vessel or umbilical cord. The mother will often eat the umbilical cord. It does not take a long time for the spot to heal. In a day or so, the area scabs over and it soon becomes difficult to tell where it was before.