You really have to nip the chasing in the bud. You can't let them do it. As long as the cats run, the dogs will give chase. One of my cats has learned not to run and the dogs are fine, but the other one is a runner.... Just yelling isn't going to do it, so I'd keep a lead on the dogs (not on a choke collar or anything that could get them hung up -- just a normal buckle collar) so you can get to them and give them a leash correction to stop it. You need to be an alpha with them -- let them know that you are the boss and this is not acceptable behavior. You can kind of stand over them (posture) and give them the meanest voice you can give (deep -- sound angry). Ever seen a dog chew out another dog for a bad behavior? Like that. And then make sure that in every aspect of the dogs' world, they know that you are in charge. Nothing in life is free. If they want to eat, they have to perform a command like sit. If they want to go out, they must wait while you open the door and walk out first. The alpha leads. If they want on the furniture, they must be invited. You eat before the dogs eat. This is all important in making sure that they know that you are in charge. When they know that, they will respect you when you chew them out over going after kitties. Otherwise, your words don't mean a darned thing because they might very well think they own you. I have had a couple of foster dogs who were cat chasers, and it was misery. One was such a knucklehead (and he jumped baby gates) that I had to literally leash him and tie the leash around my waist to keep him from going for the cats. He was impossible. Another one just needed to know that I was in charge. Still others need to have a cat ride around the house on their heads with all of the claws dug in to know that chasing kitties isn't cool.