So I'm off...

I'm sorry for you.  I once had a dog that would nip people that way.  It was only people who came to our house, so we had to muzzle her when company came over.  My current dog, Tanker, has dog aggression issues and he wears a muzzle when he might come close to other dogs (walking in the park, the vets, the petstore, etc.).  I got him a basket muzzle- they are safer  than other kinds of muzzles because the dog is able to pant and drink water.
 
Muzzeling is not the end of the world, although it is sad your dog won't be able to chase balls at the park. 

Oh Leslie I'm sorry.  The muzzle thing isn't fun (one of mine is muzzled for shots).  I've seen two dogs at the dog park wear them.  One did fabulously, the other was dog aggressive which the owners were attempting to fix with a muzzle - terrible idea - the dog was flipping out but simply couldn't bite.  The one that was a success was a rescue Rottweiler.  She was nippy with some men.  The owner was very open and honest and when people asked her if the dog was a biter she would just say "Yes, unfortunetely she doesn't love everyone," although you never would have known.  Muzzled she was wonderfully behaved and often came to me for scritches.
 
Not trying to ramble, just letting you know that you aren't alone.  Now at least the general public will be safe, and because of that, Indy will be safe. []  From what I've read on the forum you are a great owner; there may be ways you can work through these issues with consitent training.  Until then, I applaud you for being responsible!

I so sorry. Think of it this way--you are protecting Indy from himself. It is hard, but you are being incredibly responsible by making this decision. Maybe someday he will be able to retreive again. For what it's worth, this sounds to me like fear aggression. Have you thought about seeing a behaviorist about him?

Poor Indy, how can people completely ignore him??  He's so cute, I'd be all over him.  Leslie, just a heads up too, if you get the nylon mesh muzzles, be careful because he could possibly still bite through it.  Willow does. 

Aw, I'm sorry leslie.  That's no fun.  Any chance you could find a different park that is more secluded?  Or take him to a fenced in ballfield to play fetch? Scout gets weirded out by some people(thier mannerisms or they try to approach him to quickly) and barks at them. So I work on his recall and leash him until they leave or we  someplace else.  Its never fun to have your dog do something you would prefer him not to. It makes you feel like crap and its embarrassing!  Hugs to you.

Ewin... I'm right there with you... by girl barks at EVERYONE!!! However, if people ignore her, she's fine... it's the ones that actually give her attention, which is tough since she's so cute.  I also have to muzzle her at the vets, but, what are you gonna do?! She's fine with that... if we're out in plublic, she's on leash.  The dogwalker does let her off leash, but he goes into the woods, so it's a little different.
Leslie, I feel for you, but better a muzzle then the worst case scenario. Good luck!

Just be sure that you acclimate him to the muzzle - and, don't feel too badly, you can play new games and reward him with squeeze cheese.  The nozzle fits nicely through the muzzle, and it's way better than a biscuit to get cheese!
This behavior is actually quite common among the herding breeds, but other dogs do it as well.  I think it has something to do with wanting the scary thing to go away, so you just take a parting shot to be sure they're still leaving LOL.  Take heart in the fact that he does not break skin.  If he intended that to happen, it would have.
For those of you with dogs that are fearful, belong to the herding or guarding breeds, or just any old dog at all, the best insurance against this behavior is to teach a solid "leave it - come!"  It really works - last night at class, my colleague (I think she does this crap just to torture me LOL) brought a live rabbit to class.  Sequoyah left the rabbit and came to me on command.  Now, I am a trainer, so you might expect that.  BUT, most of the dogs in class were able to master this after working for the last few weeks on gradually harder exercises.