pulling and mischief

Question
Hi,

  I wrote to you a couple weeks ago about my new puppy, an 8 month old lab mix (he may be mixed with Great Dane, but that's just a guess, though the Lab part is obvious).  I just had him neutered last week, and have begun working with him on walking (heeling), sitting, down-stays, etc.  He's beginning to respond, though he's still rather bull-headed.  But the problem that I don't know what to do about is when I walk him at night (we have a big yard but no fence, and there are lots of trees and bushes where rabbits and other critters hide) and of course I can't see beyond the beam of my flashlight, but he will see a rabbit and nearly dislocate my arm!  He is big enough now but if he gains weight and grows bigger I fear I won't be able to hold onto him in such circumstances.  Now if I walk him in the daylight and see a squirrel I can prepare and yank him back before he pulls my arm out of joint - so what can I do at night? We do have outdoor lighting but there are still places that are pitch black and if there is a rabbit or ground hog there I can't see it until he flushes it out and it's too late.  How can I break him of this nasty  habit?  
 Also - I bought a "gentle leader" and have had him wear it all day so I can get control over him in the house as well as outside, but tonight he somehow slipped it off his nose and promptly chewed it to bits!  I had it tighter before, but he rubbed sores on his nose in trying to remove it.  It's a catch-22 - if I put it on so he can't remove it the sores won't go away, and if he's without it he acts like a bucking bronco.  Any advice would be greatly appreciated.

BTW - he is scheduled for an obedience class right after Thanksgiving, and I am working one-on-one with the trainer now to get him crate-trained so we can leave home without him getting into stuff.

Answer
If the Gentle leader was working on lead, I would try another, but only wear it when walking.  Leave it a little looser to protect his nose, and it should stay on as long as you have some tension.  The trainer may suggest the prong collar. If he really seems to know what he is doing and fits it carefully, it may be a good solution for you.  Poorly fitted prong collars are dangerous.  Do not try it yourself.  Otherwise, it is back to the slip collar and flip the dog over corrections, which will be more and more difficult, although at 8 months he has most of his size.  

Likely the trainer is giving you some of the same advice on the crate as I usually do.  A dog that has not been crated since it was little, make take some work.  Start out just putting its toys and treats in the crate.  Praise it for going in.  If you have been able to trust it with any bedding, put that in the crate.  Feed it in the crate.  This is also an easy way to maintain order at feeding time for more than one dog.

A good obedience class should teach you how to sell the idea you are top dog and that will help the pulling.