I don't have any guesses, but it sure as heck sounds like the dog landed on the right doorstep
Mom here...It's up for debate as to who rescued whom. Six weeks prior to finding Howie on our patio during a dangerously stormy night, we lost our 11 year old choc Lab due to kidney disease. She died in my arms at 2:40am. We'd had her since she was 6 weeks old. I was not handling the loss well and despite everyone telling us we needed to get a dog, I wasn't ready and may have never been ready. No way could I love another dog like I loved Carly. When I opened the patio door late one night and saw Howie, he ran away. I stood out in the rain and begged him to come back. He didn't. I just stood in the rain crying (over the loss of my Lab). Checked back before going to bed and he was back! This time I approached slowly and let the aroma of warm milk convince him to stay

He has healed and blessed my broken heart and I love him just as much as I ever did Carly. He is just wonderful a dog as she was but totally different. The news of heart worms was a shock! How could he be so active, look so healthy and show no signs and have heart worms? We went for a second opinion...he was positive. He's been housebound for nearly a month and we have two months to go. Might let him stay outside if it had been a different time of year but the heat (despite being in shade and with a fan blowing on him, would just be too hard on him. Our goal is to keep his heart rate down and blood pressure down during the protocol. Good thing I don't work because he has developed such a *crush* on me

that I can't leave the house without him having a full blown doggie panic attack. Heart rate and blood pressure UP! Even happens if my husband stays home with him. Doc gave him some doggie Xanax but I haven't had to use it yet.
ps...checked out the doggie DNA test and they don't seem to be terribly accurate.