When I was young we also had a cat that knocked on the door - she appeared in the snow on the day that Princess Anne got married and we played with her - the following morning when we opened the front door, she was on the doorstep, took one look at the dog and said 'if it's good enough for him it's good enough for me' walked in and stayed for 16 years!
I got my current Golden Retriever 2 years ago as a pup, and was hoping that I would be able to get him trained up as a service dog for me - however, he is scared of his own farts, so that went by the wayside! However I have now had 2 falls, and it has been him that has alerted my daughter (the Careline ringing the house phone over and over didn't wake her,) but he did as he knew that something was wrong!
My other dog is a very good bird murderer (rescue from Romania so I think that is how she survived?) so isn't let off nowadays unless I can get her to the middle of nowhere - but a few years ago I let her off in the woods where my Mum lives (bottom of Doncaster Racecourse). She disappeared off hunting so spent the rest of the time calling her - got to near the end of the circuit and someone asked if I had lost a dog? Turned out she was waiting under the car for me! Wherever we go she has ALWAYS found her way back to me despite not knowing where she is! But she isn't really safe, so unless escapes she is now on lead sadly for her!