What if the animal turns rabid? Can you shoot it in the head with the .22?
Of course. And if my house was on fire, I'd get my family out before I considered my dogs.
But I want my (adopted) boys to know they are unconditionally my sons, and that my wife is unconditionally my wife. They have talked me into adopting cats before, and then wanted to get rid of the cats when they did something unpleasant or when they got scratched. I taught them we train the animal to behave, but we don't abandon them even if they become inconvenient to us.
I have a close friend at church who began to behave poorly. My boys saw me press in and discover what was going on with him. They saw me help him face his issues and come out the other end of his situation a better man. But it would have been a lot easier to say to heck with him and let him run off his last friend.