We were told by our trainer to immediately distract Ebony via a fake "bite", like an alpha would give to a lower pack mate. It's a quick two-finger jab to the ribs, kind of like a warning nip from another dog. It lets her know she needs to pay attention to me and stop doing what she's doing. We used it a lot when she first got here and would "track" the cats like they were potential targets. One quick jab and she'd look around at us then shift her attention elsewhere. Works well on walks too when another dog is barking a lot at her or rushing the fence. Once she successfully ignored the cat/dog/whatever we lavished verbal praise on her. So far so good with the cats and her leash manners are excellent. That being said, I'm sure that strategy could backfire if the dog doesn't already know you're the boss. On the rare occasion she's having trouble focusing or the other dog is being really aggressive, it's helped to make her stop, face me (away from the other dog), and sit. As long as I'm talking to her and making her keep her Sit, she'll leave the other dogs be. Once we've re-established calm, we can move on.
~Marrow