We have a Westie that we acquired when he was nine weeks old. He was not raised with cats, but we adopted two kittens when he was six. He did not bat an eye at them. We currently have four cats and he still doesn't care.

Housebreaking was not an issue with him. Marking, however, can be. We have another dog who, for various reasons, has never been reliable at housetraining. The Westie will mark over him but does not urinate due to lack of bladder control, if you are following me. He has been neutered more than 10 years now, and that part has just never left him.