It's possible he's never seen cats before, thus not realizing the proper way to interact with kitties.
Teaching him the "leave it" command is a good one, you can use it when he goes after the kitty. Also, get someone to help you. Get some treats, and put a leash on the dog.. preferablly sitting on the floor. Have the friend hold the kitty (or you could go into a smallish room if there's no one to help). When he goes to go after the kitty tell him to leave it and yank back on his leash. When he either comes back to you on his own or looks your way give him a treat and praise. And when he's just watching the kitty give him some treats and praise him for not being mean.
Being an owner of two Mini Schnauzers and having a house ranging of 3-6 cats... they will only give chase when the cats are running, but will pretty much leaving them alone (though they do get jealous if I'm petting a kitty.LOL).
I still think the shock collar is a wonderful tool if used correctly. Please educate yourself on the proper use of the collar so you do not hurt your dog.
With my kids it worked miracles. The tone will stop them dead in there tracks now.
At first to train them I give them three tones and if not responding I give a low correction. I will repeat this and up the correction if needed.
I run on an old country road with cattle. Wiley was always trying to chase them. I was so scared that one kick or trample he was gone.
No problem now.
Blaze also wanted to chase the cats. Never had what you are going though but I put that collar on her and every time she even looked at the cats in a stocking way I toned her. If not responding she got a correction. Now she watches the cats but I say " Blaze NO, they are my kitties"
Now it is no problem. Best of luck to you.
I hope this helps! She/he bit you, and that is not good. OB classes is also great.