How long does it take for an adult Teddy to forget its old owner?

An adult Teddy will basically never forget its old owner. At this time, the dog has a memory and will remember the scent of the previous owner. Unless it is a puppy, it will not remember its old owner. However, if the new owner treats the dog well, the dog will recognize the new owner.

Dogs identify based on smell. Dogs actually cannot see too many colors. The world in their eyes is similar to that seen with night vision goggles. Dogs have a very long memory for smells, so they will remember their old owners for a long time.