> If you present him with a bill for the upkeep of 'his dog', he will run a mile. Two years of food, vaccinations, vet bills and the going rate for home board will run into thousands.
This! I had a similar experience two years ago when I fostered my brother's dog as he'd effectively made himself homeless, but having seen the state of her and the immense pain she was in from numerous ignored medical conditions (that he was fully aware of I might add) I refused to hand her back.
He kept trying until I detailed the costs I'd already incurred from getting her right, boarding fees, and projected ongoing costs for her medical problems. I haven't heard a word from him since!
ETA I should point out that like you will have, I had everything on my side re. ownership - vet records going back years, upkeep costs, and the vet bills themselves of course. I spoke to Doglaw and they said that basically, he didn't have a leg to stand on as even when she was with him, the records were in my name (he lived with me and my dad previously and I looked after her then) so to all intents and purposes, she was my dog. The only thing I didn't have was her microchip in my name - but that doesn't prove ownership of the dog, only the chip so it was irrelevant anyway!