Unmanageable On a Leash

Question
Hi. My family owns two male mini Australian Shepherds, who are four and six years old. The four year old is impossible on a leash. The second we get the leash out, he freaks and starts trying to climb things, like chairs and tables. His eyes bulge and he starts panting. If we put the leash on him, he starts rolling and biting and frothing at the mouth. He grabs a hold of the leash and pulls on it, growling. It's scary to even get the leash out when he's near. We tried to train him as a puppy, but he always hated it. It's strange, because our other dog from the same breeder behaves amazing on the leash, and loves going for walks. Thanks in advance for your advice,
Allie.

Answer
Allied,
This is very strange, somehow he was frightened as a young pup, each time you gave up trying to use the leash on him, he realized there really is something to be afraid of in his mind.
OR

Have you checked to make sure he doesn't have anything wrong with his throat or air passage.  It is possible he has a sensitive throat and he panics when he feels he cant breath.  Have you tried a harness?

Go to the store or online,  and get a calming pheromone collar and plug in.  Also get a different kind of leash entirely.  If you have a leather leash, then get a chain leash, if you have a chain, get a nylon.  Rub the leash with the pheromone collar.  Rub it long enough to get the smell on it.
  
Put the collar on the dog (if you can, if not just use the plug in)and plug in the wall unit and then bring a leash out (one he doesn't recognize)and put it on the floor.
Keep him far enough away from it so that he doesn't react.  If he is reacting, back him up a little further.  As soon as he doesn't react, give him some real turkey, liver or liverwurst, something he does usually get.  Tell him to sit and give him the treat.

Next move one step closer, give him a couple of seconds to settle, tell him to sit when he does give him a treat.  Repeat this procedure until you know where he starts to get upset.   If he gets unmanageable, back him up to where he is manageable give him a sit command and a treat and this time, have someone walk over to the leash, put it on the other dog, and praise the other dog
VERY LOUDLY AND WITH A LOT OF ENTHUSIASM, AND GIVE THE DOG WITH THE LEASH ON 3 BIG TREATS  IN A ROW, THEN TAKE HER OUT.  Mean while your dog is still in a sit.  You tell him "good sit" and give him a small treat and lesson is over.
Do this every day and only decrease the distance between him and the leash by one step at a time  
When you can get him fairly close, leave the leash on the ground and have him sit next to you while you are in a chair.  Increase the time the leash is on the floor.  
I know this is a slow process.  But you are actually probably working with a phobia.  This is a way to desensitize him to the leash.
After he can be near the leash without going crazy, go to the store and get a long piece of ribbon about the thickness of the leash.  Put this on his collar or neck and let him wear it around the house ALL THE TIME.  This will help him get used to the movement of something attached to him, without the weight of it.

I think by now  you see where I am going.  After he is comfortable with the ribbon on him.  Put a paper clip on the end to add weight to the ribbon.  Keep increasing the clips until the ribbon is fairly heavy.
Another shopping trip I am afraid.  Go online to an Agility website, or try Petedge.com or Cherrybrook.  Purchase a very short lead that is used in agility, it is about 12 inches long.  If he tolerates this, keep it on him all the time.
Gradually start leading him a little bit with that lead until he gets used to it.  Always give him a treat of turkey etc. even if he only walks one step the first time.
You should be able to continue until you can use a leash, by using this tiny steps at a time method.
good luck
nancy