Incessant butt sniffing and dominant behavior
I have a 2 year old intact male rescue who apparently has some bad dog manners. My roommate brought his 11 year old lab home 6 days ago and Duke is obsessed with him. The second he goes outside he makes a beeline for his bum or crotch and won't stop until we intervene. He's also exhibiting some dominant behaviors towards him, putting his head on neck, and tried to mount him a couple times. Other than that his behavior with him is playful, loose wagging tail, play bows, nothing aggressive.
He's too big and plays too rough for the old guy though so we have to interrupt frequently before anything gets out of hand for the lab. Sometimes I can redirect Duke's attention before he goes into full butt sniffing mode, but if I call him over and have him sit, as soon as the lab moves he takes off to start sniffing, and really just being an overbearing rude invader of personal space.
How can I get this to stop? I know dogs sniff each others butts, but this is just ridiculous. I'm really at a loss right now, it's gotten to the point where we've just started body blocking Duke from getting to the lab, and they can't be in the house together at all, he just gets way to riled up.