Opie is a master of "the look". Its been months, since he's had to hiss, spit or swat Ike. "The look" has been enough.
For his part, Ike has quit trying to sniff Opie's butt. Opie doesn't think much of dog etiquette.
When Rowdy and Ike are having one of their romps, Opie looks SO disgusted. Its like, "HOW can you carry on, with that big, dumb, clumsy oaf?" That is, completely, beneath Opie's dignity.