The animal would have to be severely fucked up for the shelter to want to put it down rather than trying adoption. That said, and I know this is going to piss you off, but fucking a dog is one of the lesser forms of animal abuse shelters have to deal with. People at the one I used to work at would even joke about the odd case of it, usually from elsewhere. I tried to keep an eye out for behaviors that would red flag someone as a horrific furfag, but I mostly worked in the cat room, and cats are a lot less sexy to the knotseeking.
For ever one diddled dog coming in, we probably had a thousand neglected, beaten, pit fighter, or otherwise truly well and abused animals. They react differently than people and in most cases were happy to just find anyone for a moment and lick their face off. If an animal is put down it's either due to health/space issue, or he bit someone, and gets put on a 10 or so day hold to check for rabies before getting put down.
