How we deal with lower life forms on our own planet is totally unrelated to how we would deal with intelligent life from another. Why would they be related? If you're worried that aliens would look down on us as inferior life forms and wipe us out, that's totally possible, though I'd say it's pretty unlikely that any aliens ever come to visit us anyway. If they do, and they're more powerful than us, our animal welfare laws are not going to do us any good.