Open Mike,
There was a "railroad" dog who turned up as a stray one day. The trainmaster adopted it and the dog road the rails for years as a celebrity. It even went to Europe and was presented to the Queen if I remember right.
Back in the states it was shot by a railroad employee who thought it was a stray.
I will have to see where I found this story. If I am right, the Smithsonian has the dog's remains.
All very vague but I will search. Might be your puppy.
Mary