Jack Russell w/ One Issue

I have a 3 year old male Jack Russell and he is a great dog. He goes with my wife & I 24/7. Work, home, boating, & traveling. He's been great and minds well. He has never tried to bite anyone (since his first attempt as a puppy which I put a quick halt to that behavior) including little children that crawl all over him and pull the ears. He's great with other female dogs, BUT when it come to male dogs he has some trouble. He moves right into the sniffing thing and sometime they get agressive. If another male comes to visit in our house he get really agressive about food and toys. He get so focused that he will follow them around and try to pick a fight. Even if the other dog is 75lb pit bull. (He's 15lbs and thinks he's a 100lb Pit Bull) He's not been fixed but he has an appt. for two weeks from now for the deed. (Poor Guy)

Question, is there anything I can do to break this or is that the nature of the beast. Now I yell, slap and break up the fight but that seems to do nothing for the next time. I have a shock colar I used in his training days but once he starts to fight he can't feel it and thus it does no good.

He's such a great dog I hate to see this side of him. he's 99% Dr. Jeckel and 1% Mr. Hyde

Any help would be great....

See attached picture,

One more shot of Skipper climbing a tree in search of a Squirrel.....

He's focused...

I have owned several Jack Russells and still have five. What you are describing is typical behavior for the Jack Russell breed and most other working Terriers for that matter. They have sharp fiesty temperaments and there is not much you can do it is a genetic trait, just avoid confrontations the best you can.

You really have to be careful using an e-collar to break up a dog fight. It can be like throwing gas on a fire to put it out. It makes gritty game dogs like Terriers fight all the harder because in their mind their opponent is causing the stimulus.

Yep, Airedale has it right, but I would like to extend it to most any creature. You just can't bring another, dog in this case, into another dog's territory and not expect some confrontation. That is the absolute worst way to introduce them. Especially with an unaltered, adult male.

Another common mistake is for people to get antsy and separate them before they have done enough sniffing and posturing to decide by themselves who holds higher rank. I have never understood the multi-dog households that have to take turns letting their dogs be with them because they never learned to coexist. In most cases it's because the owners never let them determine rank amongst themselves, so everytime they are together they still need to figure it out and then get separated right away.
The breeder of two of my dogs used to turn loose a group of strange dogs in his field and they were all playing together before long without any human interference, but of course there are some dogs you would never do this with just like there are some people best left to themselves or behind bars.

The countries on the other side of the Atlantic are so far ahead of Americans when it comes to raising dogs that sometimes it ticks me off we are what we are (when it comes to dogs). You would never hear of someone wanting to sue someone else because their dog bit another dog at the restaurant.
In the US we have to think so much about liability issues that often times are pets are not properly socialized and have no idea how to behave around one another.

Hope I didn't get too political here.

Oh, and chances are that castrating your male won't alter his behavior at this time in his life, but it's still a good idea.