You know, I guess one of the quirks of being transgender and one of those vegetarian/sort of vegan, animal rights/welfare weirdos, is that my sensitivity to pronouns extends to other animals.
I feel really uncomfortable when people refer to non-humans as "it." It just makes me cringe.
She, he, or they conveys the respect of seeing them as living, feeling individuals, just as you or I are.
And that's why human's call other animals "it" I guess. We don't want to extend that status to them.