* "Chien en fer-blanc" - This literally translates to "tin dog" and would be understood by French speakers, but it's not a common phrase.
* "Chien de fer" - This means "iron dog" and might be used if the context implies a dog made of metal.
* "Chien en métal" - This means "metal dog" and is a more general term that could be used to describe any dog made of metal.
If you can provide more context about what "tin dog" refers to, I might be able to give you a more accurate translation.