Our McNab border collie is quite protective without going over the top with anyone we approve and he chases, when I let him, the neighbour's cats but not his own. I have had to be top dog with him about that when he first came into our home, but that was years ago and the cats have been lovin' up to him ever since. Now, if they were outside cats it might be a different story. So, with a herding dog I would definitely get a puppy to be raised with the cats, as others have recommended. He is by far the smartest, least demanding, amiable, quiet and sensible as well as fiercely loyal dog we've ever had. When it comes time for us to have another we have decided it will have to be another McNab.