Just the contrary: humans are the only animals that have non-recreational sex with the intention of producing babies. Other animals don't know this, so they're all just having sex for the pleasure of it.
so none of you have had your leg humped by a dog who is clearly loving it?
you think it thinks it is copulating?
as has been stated, it is arrogant to assume that animals don't get horny and enjoy a shag.
i doubt many animals give a toss if their sperm has produced offspring - many just walk off - they don't go back to check.
and i doubt half of them even know thats what may happen anyway - they will only know from what they learn or see - they are not psychic and 'just know'
our closest relative, the Bonobo Chimps use sex for recreation and reproduction. Female bonobo's have been observed using sex as a way to defuse argements and disputes, they also use sex as a greeting. In fact the Human and Bonobo females are the only female animals that can experience an orgasm. That last point really scared me, no-one told me women could orgasm