It's hard to say....... I have a B .Collie/Lab mix, who is 3 yrs. old. I have only had her for 4 months now. When I brought her home, it was clear that she had not been around cats (I have 2 cats). She either wanted to chase them or she did growl a couple times. We had to keep them all seperated for quite awhile. It helps a lot if your cats are indoor only. Also, we kept the dog in a crate when we were gone or could not watch closely. With all that being said, they are now friendly with each other. It took a good couple months at least. One of my cats still does not LIKE the dog, but will tolerate her. My other cat likes her quite a bit. In fact, the other night, my dog shared one of her treats with the kitty! Very Cute! Anyway, good luck and let us know what you do.