Teaching an emergancy down

Question
I wonder if you could please explain how to do this both where the dog is coming towards you - my dog knows the hand signal and the word but she totally ignoes me shouting and hand gesturing 'down' at her when she is running towards me - she carries on running right back to me and then she lies down.  

Also, can you please explain how to teach an emergancy down when the dog is running off and locked onto a prey object? My friend's dog recently got hit by a car chasing after squirrels and it really made me think that if she could have stopped him and got him to go down it would have saved him from alot of pain and suffering. Many thanks.

Answer
If the dog is running off, and focused on prey, it can be too late.  In that situation, you really need an emergency recall that has been conditioned over time, and you need to issue the cue for it with lightning speed before the dog's brain is impervious to hearing it!  The first thing to do is teach the dog to turn her head and look at you when you say her name (go to www.clickerlessons.com and do the "Attention" exercise.)  I teach an emergency recall by using a whistle.  For a month, at least, several times per day, I simple sit or stand next to my dog, blow the whistle and hand the dog a treat (this treat should be something the dog goes gaga for, and which he/she rarely gets, say roast beef or tripe even).  Don't use the whistle to call the dog - this is Pavlovian.  All you are trying to do, initially, is condition the dog to know that once the whistle blows, she will get her treat.  Eventually, you could hope to get the dog to come when she hears the whistle.
To train a regular recall, I use the method on Leslie Nelson's DVD, "Really Reliable Recall" - you can get a copy at www.cleanrun.com.
As to the emergency down, you start by teaching it with the dog relatively close to you.  Do NOT shout or gesture - that can frighten or confuse your dog, and make her want to get to you more for security.  Instead, have her sit in front of you.  If she is good at doing a "down" on voice cue, simply add the raised hand cue before you say "down."  (When you transfer cues, it's always done "new cue, old cue")  As you see that she is anticipating, and going down as soon as your hand raises, then you can dispense with the voice and just go to the hand signal.  Once she has that, you can put her in a sit/stay, and step back a step or two.  Give the "down" cue, as you step slightly forward with one foot.  That should be enough of a body language suggestion that she should not come forward, but can still go in to the "down."  If she does it, jackpot her with a few great treats.  Next training session, try it again, and if she's successful, reward her and start gradually building the distance between you and the dog.  Until the dog is uber reliable at both, she should not have freedom off leash in any unfenced area.