my dog bites the leash

Question
How can I get my dog to stop biting the leash when I put it on him to go for a walk. He walked fine the first week we had him, but now, he bites at the leash.  We've tried a regular collar, a chest harness, and the Gentle Leader head thing.  He still bites and tugs the leash!

Answer
For a long time, this was part of my standard advice for dogs that pulled on lead:

Easier dogs will give up their pulling with a few good snaps of the leash
combined with a stern "Bad dog!".  You can work up to forceful corrections
with the leash doubled up in both hands and your whole body behind it.   But
you don't want to use any more force than you need.  One gentle technique I
like is to just stop when he pulls.  He wants to go.  If you move forward when
the leash is slack, and stop when he pulls, he should quickly figure out the
only way to get to go, is not to pull.  This is about teaching him not to
pull, not getting somewhere.  The man that taught it to me said "If in a half
hour you haven't made it out to the front walk, fine, you have taught him a
lesson.

Never snap the leash if you are using a Gentle Leader or other head collar.  The above should work with the biting too.  Some people suggest turning around and walking the other way.  At a training seminar I went to last fall, The presenter gave a very effective demonstration of walking backwards when the dog pulled.  You should have seen about 70 of us working on it out in the parking lot.