I had a dog (ex husband kept her in the divorce) who would regularly break out of the yard to go play with other dogs in the neighborhood.
One day she comes back home...with another dog. Just a happy pit bull with a collar, but no tags. Friendliest little boy.
I start going door to door to try to find his home.
Discover that some people had moved and just left him. They'd actually, we later found in checking the fence work...left him in his yard. Between the two dogs, mine had helped him break out.
I already had her and a pup I was housebreaking, four cats, four chickens, and pet rats. A third dog was just not in the cards. Thankfully another neighbor was willing to take him. Sadly, this happens so often. People have to move and don't bother ensuring they move somewhere that pets or allowed. Or if they must move somewhere (health, family, etc) that pets aren't... To find a new home for their pet.