I agree completely with Ingrid.
My BrightStar boy, Trace is a hard, stubborn, high drive boy (just the way I like 'em..) and I brought him home to my cats. My God, he wanted to
kill my cats when he came in the house. Failure is not an option in my house, so he was tethered to me by a 6ft leash and a prong for the first 2 weeks in the house. When I could devote my undivided attention to him, he was on his prong & leash. If I had to shower, vacuum, or do something around the house, he was in his kennel.
The minute he looked at my cats funny (you know
that look), he got a very firm correction. If he dared to go after the cat(s), he was met with a very,
very hard correction. This went on for 2 weeks, to the point where he settled down a bit. I then let him drag his leash around the house for another couple weeks, but only after I knew how to read his body language towards my cats. With the leash & prong still on him, I could quickly grab it should one of the cats come strolling in and correct him if need be.
Today, he is fine with my cats. My one cat even curls up with him every chance he gets. He learned early that my cats are off limits. Of course I would never trust him, or any dog for that matter, being home alone with the cats. He is kenneled when I am not home.
This method is for a high drive, stubborn dog. You may need to adjust depending on your dog. I do recommend having the on a leash and some type of correction collar - for just that,
correcting the dog. If a cat makes a sudden move and your dog goes after the cat, you are absolutely powerless unless you have some kind of collar and leash on him/her. Sometimes voice commands do work, but also remember sometimes the dogs drive overcomes that and then you have an injured or possibly dead cat. With a leash & correction collar you are doing 2 things - taking away the possibility that your dog may injure your cat, and also teaching the dog by correction that they are off limits. It's not easy & takes alot of time & patience, but having that piece of mind in the end is all worth it.
I have a high drive female foster coming soon, and I'm looking forward to teaching her to co-exist with my cats!
Good luck!