how long should it take to train my dog?

Question
Hi.  My boyfriend and I recently acquired a boxer pup from my mom because she bought the dog on an impulse and didn't understand the amount of work and attention they need.  We work opposite schedules so someone is always home with her and have a great fenced in back yard for the dog so we decided to take her.  She is about 5 months old and graduated from puppy school at Pet Smart.    She can do tricks such as sit, leave it, drop it, lay down, shake, and roll over but will only do them if she gets a treat.  That is fine with us, but our problem recently is the fact that she aggressively attacks us when we go out to the yard to play with her.  She has torn up most of my clothes to the point where I have to wear the same tattered clothing to go out there in fear of loosing my entire wardrobe.  I have read alot about training and learned alot at puppy school, but nothing seems to be working.  I cross my arms, turn around and make no eye contact with her but she just keeps on jumping and biting.  I then calmly walk inside and wait for about 5 minutes and try again.  I have so many bruises and cuts from her little puppy teeth that my boyfriend wants to get rid of her.  He is fearful that as she gets bigger she is really going to hurt me.  She is great when we go on walks- doesn't ever bark at people or animals, is very submissive with other dogs (we take her to a dog park once a week) and is great when we take her places. We crate her at night and she never pees in her crate but she stays outside during the day.  She gets 2 long walks everyday and lots of attention.  I know she is trying to assert dominance but this has been going on for 6 weeks now and nothing is changing- so I guess my question is how long does training normally take with boxers and should I try another method other than the positive reinforcement with treats?  We do not believe in striking or pinning down as methods because I would think this would increase her aggressiveness with us.  I asked our vet and she said just keep it up and  have patience.  I think 6 weeks of consistency and still encountering bad behavior and hurtful biting is enough to make anyone loose their patience.....  Thanks for reading this long story, I would appreciate any advice from anyone at this point.

Answer
Hi Angela,

I really don't think this is dominance at her age; it's more likely just an overabundance of exuberance.  You're on the right track with ignoring her and leaving the area, but you might try making the 'gone' sessions shorter (say 1 minute) and a first step (rather than turning your back first, which obviously isn't working).  It may drive the point home faster if every time she jumps on you, you disappear, rather than giving her a few jumps and then leaving.

That said, some dogs just need a different approach.  I had one girl like this, and whenever she would start jumping I would tell her to get a toy (and, of course, get it for her at first until she understood what 'get a toy' meant) - she can't bite and hold a toy in her mouth at the same time.  Then I'd praise heavily and we'd play a little tug.  Now (she's 7.5 years old) when I come in the door she greets me with a toy in her mouth, wiggling like crazy. :)  

You could also teach her to retrieve, and you can then toss a ball for her to chase instead of jumping/biting; or any number of other, incompatible with jumping/biting, behaviors.  She is obviously a very smart puppy, so you really need to focus on what you want her to do, and train/reinforce heavily for that, rather than trying to stop her from doing what you don't want her to do.  

You mention that she stays outside during the day, while one of you is home - while that's safer than her staying outside while no one is home, it may be contributing to the problem because it creates an odd dynamic/relationship, and makes your appearance in 'her' yard that much more exciting.  If she were around you all the time, in the house or out, you'd probably be less thrilling for her. ;)  Of course I'm sure you're aware that Boxers don't tolerate extreme heat and cold well, but since you're home you'd be able to bring her inside in those conditions.

Some resources that you might find helpful are:
"Bones Would Rain From the Sky" by Suzanne Clothier (book)
"The Other End of the Leash" by Patricia McConnell (book)
http://www.clickersolutions.com Training Articles (website)

Good luck!!