Squirrel chaser

Put a leash on her, and start working on attention.

She should probably wear a leash inside, too, if she's getting that wound up. Then, you can move her away and distract her with something more productive, like a game of fetch.

I would put her on a training line and work on the 'come'!!
till she is hundred percent...
  then move up a stage, taken her to the park or where you are likely to see a squirrel, and work on come with this distraction, given her plenty of praise when she comes back...
 
These distraction's and her need to retrieve is vital!  it could save the squirrel's life and you dog's...
hope this helps, Lance..

I agree with the other posters.  Put her on a leash and keep her on a leash when she is outside.
 
I had a couple of APBT's that would, on occasion, bring in a dead squirrel, who had happened to pass through the back yard, while they were out to potty.  It was delightful.  [:@]

Sounds like your lab has a very high prey drive.  She needs to be on a leash at all times outside.  If her prey/chase drive is that high, you might consider carrying high value treats on every walk.  When you notice a squirrel or other preferred quarry, get your dogs attention on you...give the treat and lots of praise.  This won't eliminate the prey drive, but it will help you so that you can get your dogs attention on you some of the time.

Thanks a lot for the advice. She's on a leash 99% of the time she's outside. I used to let her walk out with me from time to time without one, but not anymore. I'll start working on getting her attention when she's distracted and carrying treats to train with on our walks.

 If you do a lot of reading you'll notice something interesting: people who claim you can train a dog to recall off prey-in-mid-chase using nothing but positive reinforcement so often seem to have herding breed dogs. Dogs who were bred to be able to be called off stock easily. Everyone else admits that a high-prey-drive dog is going to laugh at your treat if he sees a squirrel. That's why they invented long lines and remote training collars. Basic obedience work and work on self-control and paying attention to you will help. But you may want to do a little research into methods used to train hunting dogs to not chase the wrong species.

Well, yes, I can call my herding breed german shepherds off running prey.  But, I could do the same with my cockers (originally hunting dogs) and that doesn't explain Jennie being able to call her JRT off running prey....all with +R methods.

ORIGINAL: glenmar

Well, yes, I can call my herding breed german shepherds off running prey.  But, I could do the same with my cockers (originally hunting dogs) and that doesn't explain Jennie being able to call her JRT off running prey....all with +R methods.

 
I am completely and totally envious of you.  If X is in full flight after something...let's just say that even an act of god won't call him off, unless he's on a leash.

We've looked into shock collars. Is that the same thing as a "training" collar? We were kind of leaning toward that idea. I'm assuming that its better to give her a little shock now than to have her rip the leash out of my hands and sprint out in front of a car later. We're doing a lot of research into how they're used and what the best methods are. I've actually met a few hunting dog trainers, and specifically black lab trainers, and they used the collars.

yeah. Don't call them "shock collars" because modern collars aren't like the old torture devices and it makes people think you are being cruel, not kind, in working to help keep your dog safe. Most folks call them ecollars or remote training collars. Not a shortcut, not cruel, needs expertise to use. I too, like Xerxes, have experienced dogs that would require an act of god to call off running prey. Or several months of careful work with long lines and remote collars.
 
Yeah, I also know of a few non-herding breeds who were trained to call-off-chase using strictly + methods. It's possible with a select few specimens, just as it is possible there are some border collies out there who will never be safe off leash near squirrels. It's also easier to do using strictly + methods if you start with a pup and never let him successfully get away with chasing squirrels-- too late for this adult high-drive lab.

ORIGINAL: ccr61

She's run across the road in front of a car to chase a squirrel before. It's like she can't hear me at all when she sees one and won't stop.

 
There's been a fair amount of study done into this "not hearing you" situation.  It's kind of like if we're totally absorbed in a movie/book/job, and someone calls our name.  We might kind of vaguely register it, but it will often take a tap on the shoulder to actually get our attention. When the dog is totally focused on hunting, it will screen out all other stimulus unless they are relevant to his hunt (or a danger to him).  Sorry if I'm not explaining it well, hope you see what I mean?
 
Anyways, after struggling with my high prey drive poodle, I reluctantly started researching e-collars.  I realised just how ignorant I'd been about them, imagining horror stories of my dog writhing on the ground twitching limbs etc.  I researched, I spoke to ppl, etc., and bought a collar.  It does take judicial use, good sense of timing, keen observation of your dog etc.  For me, it turned out to be a great tool that helped me work with my dog to overcome this problem. 
 

Any suggestions on a good e-collar type, brand, etc? What should I be looking for when picking one out? You can also feel free to tell me to do my own research, which we're already doing. I'm just wondering if anyone has any suggestions for me.

Thanks for all the advice so far.

I can only tell you based on my own experience, some of the others here might have more specialized info.  I would recommend you get a collar that you can adjust the intensity level at any time, rather than one where you set the level before you put the collar on the dog.  This gives you more flexibility and is kinder to the dog.  If your dog likes water, get one that is fully waterproof.  Some of them have a "beep" or a "vibrate" feature, that you can use in conjunction with the stimulation.  This might be useful, as then you can start using just the beep or the vibrate as a warning, without needing to use the stim.  Buy the best collar you can afford, rather than cutting corners and spending more money in the long run with upgrades.  Some companies sell on a lease-to-buy basis, so that if you return the collar after a few weeks, you get a partial refund. 
 
Something I found useful to do before I even used the collar, was to think think think about it.   Observe your dog, observe the environment, think about exactly when you'd use the collar, etc.  This really prepared me for putting the theory into action.

My border collie/beagle mix Zoey used to loose her mind when she saw squirrels on our walks- she would thrash around and scream- it was quite embarrassing!  Using only positive methods over the past three months she has progessed to just pulling towards the squirrel and has stopped thrashing and screaming.  I am now working on her pulling.  While I don't believe she will ever be trusted off lead, due to her genetics, she has improved greatly using only treats and training.