and we're steering towards "they just tolerate it" already, yay!
by "letting them decide" i mean just that. leave enough room for a "no" and don't force anything, ever. it's obviously not very natural thing for them (tho there are plenty of cases of male dogs copulating together all the way to a tie so what do i know), doesn't mean they can't enjoy it... or seek it out.
not that you'll believe me, but my current boy does flag... anal initially wasn't even my idea, he likes getting his rectum and perineum rubbed and i merely tried how far he let's me push things.