I've found this to be a very common tendency.
I've always felt attracted to human females, and as a teenager I found out I was into male dogs (and other animals) as well. Turns out it's an "animal only" thing for me. I'm polyamorous, and one of my girlfriends has another boyfriend, who is bissexual, but only feels atracted to men in a passive way (he doesn't like kissing guys, nor fucking guys, just giving oral and receiving anal sex); we did have a couple menages, but even though I could bring myself to fuck a dude, it was 'half-mast' all the way, and the idea of a guy fucking me is not sexy AT ALL, which is funny, because if I see a big dog crossing my path, I feel a very strong erotic charge.
Tl;dr: Yea, I also consider myself a straight person in human context, but a pansexual in zoophile terms.