I'll tell ya how! It's called the word "NO"!
And, YES, the dog SHOULD be collar conditioned before just shocking the crap out of him!
I've never seen a thread with more useless advice! Sorry,...but "shove a rabbit down his throat"!!! Wow!
In case you don't know how to collar condition a dog, I'm gonna give you a quick cliff notes version, for the dog's sake.
First off, figure out what setting he feels. You're looking for the slightest reaction. Every dog is different.
Next, he needs to KNOW a command. I like "kennel" for collar conditioning.
Start him 5-10 feet from his kennel and command "KENNEL" and immediately press the continuous stimulation until you see him MOVING TOWARDS, or even INTENDING TO KENNEL, and then IMMEDIATELY let off on the stimulation.
After a few times (but keep this up until you know he's learned it), he will have learned that COMPLIANCE TO THE COMMAND will stop the stimulation.
He learns that HE CONTROLS IT!
After "KENNEL" is conditioned, move on to another command THAT HE KNOWS. But, don't TEACH the commands this way. He must already know them, so if you haven't taught any commands yet, you need to back up and start some basic obedience. THEN, overlay it with the collar.
I've seen every one of these old tricks done on coonhounds, and none of them work. I've seen dogs beat with possums, I've seen skunks tied to collars, they just don't work. Teach the dog and let him learn!
Hunt where there aren't any rabbits...give me a break!!
And, in case you didn't know, your dog was originally bred to hunt rabbits! You can't blame him for wanting to chase something he was designed to chase. You've just got to teach him that it's not desirable.
Something else that I don't think was mentioned. The dog's age. If this is a young pup we're talking about, I wouldn't come down on him too hard. Let him build that fire of enthusiasm, but work on your obedience.