I loved The Adventures of Rin Tin Tin on TV as a boy in the 1950s. It was very popular.
I found out a few years ago the main German shepherd in the series was not a descendant of Rin Tin Tin. The main star was the trainer’s dog named Flame Jr. The actual Rin Tin Tin (IV) may have been used as a stand-in or stunt dog.
Really? Interesting. Thanks for the info.