How long does it take for a dog to forget its owner?

It is impossible for a dog to forget its owner. No matter why it is separated from the dog, when it meets the dog again, it may be a little strange, but only because the dog's memory mode is different from ours. Dogs identify themselves by smell. No matter how long a person goes out and how his appearance changes, the smell will never change. So no matter how long you are separated from your master, the dog will never forget the first master.