Can animals be gay?

I remember having a dog that was horny as hell and would hump anything it saw (even another male dog) but, I don't think that means the dog is gay, right? I know there has been scientific studies on wild animals that have displayed "gay-like" behavior but is there any factual evidence of animals being (or becoming) gay? Its kind of hard for me to think that animals could be gay, just seems illogical. Idk.. just found this topic a little interesting.

***Excluding HUMANS***