We had a BIG neutered male cat when we got Sophie as a puppy. Our cat, Reeses, is a very sweet guy, but I had seen him chase and hold down another cat once and was worried what he would do with a puppy. He didn't do anything. However, once Sophie figured out that he wasn't a threat, Sophie became Queen Bee, and I mean that literally. She watches his every move and lets us know if he is into things. She won't let him near us (jealous) and won't let him sleep with us, even though they will both sleep on the bed (at the same time but not next to each other) when we are not there. They get along okay and do just fine as long as we don't pet or hold Reeses when Sophie is around. If she thinks we are giving him attention, she will attack him.
He has never been aggressive toward her. Sophie is 7 1/2, and Reeses is about 14.