If you've not read it already, you might be interested in the book Other Minds by Peter Godfrey Smith. It's an attempt at tackling a bunch of questions in the philosophy of mind by studying non-human animals that clearly display intelligence (whatever we mean by that exactly), but of a very different kind from what humans have. Specifically, octopuses.

I personally found it to be extremely interesting, and while it doesn't completely close the case (very little in philosophy is ever definitive) it certainly elucidated my own thinking on questions like these. (It also doesn't get much into ethical considerations or anything, but I think you can draw your own conclusions on that front based on your own values and the arguments presented in the book.)