I got a dog on Saturday, at about 9am. I lost it at about 7.30pm the same day. This was not quite as careless as it may sound.
The hound in question, a border collie, turned up on my doorstep. No owner was present, nor did a quick look turn up any devastated individuals seeking faithless runaway pooches. I fed him, played with him a bit, took him for a walk in the hope that he would just head towards his home (to no avail: he would only cross roads when told to, and I later found out he walked right past his house in any case). I took him to the vet to check for an ID chip (he had no identification on his collar), and reported him missing via both vets and police. Then, as seems to be the case with collies, I spent the day alternately exercising him and providing feet for him to sleep on.
I was sold. Intensely intelligent and incredibly obedient, he would settle into the footwell of the car at a single command, walk (almost) to heel, fetch, stay, sit and more. I ended up teaching him stuff in French just to see if I could rule out him already knowing the commands. He put up with the aggression of one cat and relaxed happily in the presnce of the other.
We'll miss out the rest of the man-and-dog bonding that followed. Suffice to say that I took him for a walk that evening, down by the water of Leith. Once off the lead, he scarpered. Right to his owner, forty yards down the path. He was delighted, and I pretended to be pleased, but I was actually gutted. On the upside, I have decided to get my own one, which I can call by a more sensible (read, pretentious) name than the temporary monicker I reluctantly assigned at the insane prompting of a friend.
In the meantime, take a look at this (explanation is here). I stripped it from javascript to make a postable link, so use the link on the second page if you have problems.