We have 3 cats who are all somewhat ornery. The oldest is a 13 year old Manx who is pretty set in his ways. 3 weeks ago we brought home Charlie (5 months). The cats were wacky at first. We had a baby gate up to block the upstairs, and usually shut the downstairs door so Charlie only has access to the main floor. The cats holed up upstairs, bravely venturing downstairs to eat & potty.
Anyway, slowly they are coming around although they still detest the dog. He just wants to play but they are pretty intimidated. I imagine having something 6 times my size bouncing all over trying to chase me etc. ACK!!!
Our breeder has placed boxers into homes with cats before, and she said it will take a long time. Basically the cats are maintaining their dominance, and teaching the dog that they are not "toys". Growling, hissing, and the occasional paw smack
from the kitties have taught him to leave them alone. Now he just looks at them and wags his tail at 900 MPH lol.
I guess my point is let the animals figure each other out. Eventually they will. And yes, having a high place for your cats to escape is a must. They need to feel they have a safe place.
Also, we have found it is important to our cats to have one on one time with my husband and I. We try to each spend a minimum of 5-10 minutes per day with each kitty. I want everyone, humans and animals alike to feel special and welcome in my family.