"Homosexual experience" does not HAVE to include full on sex, dudes.
Also, male dogs will often hump anything that will stand still long enough, male or female, dog or other species. If they can mount it, they will hump it. If you have a male dog that has never humped something non-female dog, than you should probably check to see if it is still breathing. The same can probably be said for any other non-monogamous creature that is horny.