iI have two dogs and no cat problems at all! No I have never taught or encouraged them to chase cats but the cats stay away anyway. I also have have an ultrasonic cat scarer at my pond which is very effective at deterring cats(the pond is fenced off from the dogs as they are both avid swimmers) You can get a thing that has a motion sensor that will squirt the hose when triggered but I'm not sure its cat specific. My sister used the gel crystals stuff, I think its called "get off my garden" which she finds quite successful.
An aquaintance suggests...Attractively baited mousetraps at points where cats enter. (You might want to slightly reduce the strength of the springs first). After they're sprung, just leave them lying about. The mere sight of them will be enough to scare the cats away in future. Er, naturally I was shocked by his suggestion.
Some garden centres sell Lion's poo! I've never used it but it's supposed to be brilliant because the cats think/realise a bigger 'cat' has been there so don't poo.
Shotguns or flamethrowers work a treat. Then impale the cats head on a spike so the other cats in the neighborhood learn that you are one human not to be messed with. They'll back down and run scared and you will have won!