7 Year old Boxer - Lost Cause?

In central NJ, St. Hubert's is an excellent dog training facility with behaviorists that will assess individual dogs with issues.  They feature obedience lessons for all levels.   It has been many years since I have used their services, both for assessing my then "fear agressive" girl, and subsequent obedience classes which we attended, which saved "our" lives.  That was more than 9 years ago.  I do not know of individual trainers out of St. H's, but I know they are a reputable and positive training school.  They might be a good resource for you.
 
Mostly on the advice of this board, three years ago I sought out a trainer, much like you are doing now, for my 2nd addition, Murphy who had dog aggression issues while on leash.  I learned a ton from this trainer, but not enough to recommend her.  Long story short, there is hope for you and your Boxer.  Good for you for reaching out.  Someone else can tell you the dog trainers association that you can seek out for specific certified professionals...it escapes me now...APDT??? maybe?
 
Stay strong and know this.  After 7 invested years in your pup, it is not too late, nor is it ever too late.  You have found yourself at a great forum where you will be served by many who have been in your shoes.  Stick around for some sound advice. 
 
Much luck...pndhounds in NJ

Thank you for the advice and the words of encouragement pndhounds!  If your reply is any indication, this is definitely a great forum!

Hey there,
I can't offer you any training resources, but for what it's worth, I'll give you what I can.

I'm currently battling fear aggression with my own dog. She's 3 years old now, and I've been trying to help her overcome it for about 2.5 years.  Her aggression is only towards other dogs, and I am confident that an attack by another dog when she was 6 months old has a lot to do with it.

Honestly, we've only been making progress since I started posting on this forum. 6 months ago, it was very difficult to take her for walks. Even if she saw a dog that was 500 metres away from us, she'd go into a growling, barking fit.
Just a few days ago, I took her for a walk in a highly populated dog area (on-leash). She did not growl even once.  Granted, we did not come any closer than 15 metres to any dog, but it just shows that she's slowly getting over it. And I couldn't be happier []

Sorry I couldn't be more help, I just had to assure you that your pup is not a lost cause.
The saying "you can't teach an old dog new tricks" only applies to some people []

Hi there, I am not a trainer either, but I wanted to offer words of encouragement as well...  It does not sound to me like it is too late for your dog at all!  I would get some books on the subject (to help you understand why your dog is acting the way he is and to help you get a basic understanding of what you can do to help calm the dog and increase his confidence).  If what is going on is indeed fear aggression (what it sounds like based on the limited information you posted), a good behaviorist can help you analyze it and develop a strategy to begin to desensitize your pup.  Then, you can start things like obedience classes or, if your dog can't be around all those people and dogs yet, you can start training your dog, so you are in more control of the situation when your dog comes into contact with new people...
 
I know this is very abstract, and there are many on the forum who will be able to give you much more concrete advice here - but you should know that there is help out there and I am sure advice from here coupled with work with a good trainer or behaviorist in person will really benefit you and your dog! 
Good luck and welcome to the forum []

wow, more great tips, thank you for the info sierra and schleide.

Schleide, you mentioned 'books on the subject', can you recommend any?

In conjunction with working with a professional (someone who uses positive training methods), these are some books, most of which were recommended to me, and are often recommended to others on the forum, that I have found helpful in dealing with my dog, Wesley, who also has some aggression issues:
 
Re the aggression:
 
"Click to Calm"  by Emma Parsons
"The Cautious Canine" by Patricia McConnell
"Scaredy Dog" by Ali Brown
 
Re general background on dog behavior and the basis for all human/dog interaction:
 
"The Culture Clash" by Jean Donaldon
"The Other End of the Leash" by Patricia McConnell
 
I am sure there are others and some may be more applicable to your situation, but maybe go to a local bookstore that might have a few of them and leaf through or look them up online first to see which might be the best bet for you...
 
Keep posting on progress you make and on setbacks - it often helps to get others' perspective...  I am confident, and I have found with my own situation with Wesley, that the more you know and the harder you are willing to work, the better results you can get...  That is not to say that every dog is capable of being the "perfect" totally friendly, easy going, happy with strangers dog, but, that you can probably get this situation to be a lot better than it is now with some hard work...
 
 

Hey Harkov...
 
Just wondering how you and the Boxer girl are doing?
 
pndhounds

it's only "new visitors to the house" that get jumped on? is this really aggression, or just an over-excited "I don't know how to control myself" behavior?  have you tried teaching the dog to "sit" politely when new visitors arrive? Patricia McConnell has a little booklet on teaching your dog self-control.

St. Hubert's is top notch, and Pia is EXCELLENT!!!!!!!!!! Go there - few dogs are a "lost cause".  You may never make a social butterfly out of this dog, but I bet you can make things better than they are now.  Go for it!