My golden retriever loves my piggies. They climb all over him as he just lies there and stares at their antics
, although i would never leave them in the same room together alone because I am just paranoid. I introduced them by securely holding my guinea pig in my lap while my boyfriend brought my dog in (leashed) and let him gently sniff an investigate them (i wasn't sure how this would go because he sees cats and squirrels as something to chase and eat
) Every time I thought an he began to get a little rough (like licking and nudging them) I would pull him back and tell him he is a "bad dog", he knows what that means.) So he knows that he must be gentle when interacting with him, but i always watch them when they are together to ensure he remains to be gentle with them.
I too live in a small apartment. We make many trips to the dog park and also many laps around the neighborhood to burn off his energy.