Puppy aggression!!

I recommend you find a trainer or behaviorist for help.  It's really not possible to give you any meaningful advice without being able to see the dogs and how the entire family interacts with all the dogs.  It sounds like the new puppy may be doing some resource guarding.  You can do some counter conditioning to help the pup change his behavior.  Don't punish the pup for growling.  

These two are links to sites that you can use to find help.  Please only use a trainer/behaviorist who uses positive methods.  

ccpdt.org/index.php

http://iaabc.org/

An article on resource guarding.

www.whole-dog-journal.com/.../Resource-Guarding-Behavior-Modification_20368-1.html

Hi I agree with Jackie in the meantime try walking them together as much as you can. Please keep us posted. Good luck.

If  we didn't live in the northern Indiana countryside, I'd be walking them but...30 days 'til spring right? Woohoo! As for the trainer, I guess I'll have to call the local animal shelter and ask for cheap referrals.

Choosing a trainer because they're cheap is not a good idea.  You might get lucky and find a decent, positive trainer but you might get someone who is calling themselves a trainer and really isn't.  Bad advice from a bad trainer is worse than no advice.

Spending money on a good trainer is as important as spending money on necessary veterinary care.   More dogs die because they are put to sleep for behavior problems than die of disease according to some sources.  

If you can't afford it, you really shouldn't have gotten another dog.  If you can't afford a trainer, return the puppy before the behavior gets any worse so that someone else with the resources can provide the necessary training.  Hopefully, this pup came from a responsible breeder who will take the dog back.  

With four young children, you have your hands pretty full.  Changing behavior is time consuming and requires a committed owner.  I'm not saying you aren't able to do it but I think you need guidance from a good trainer.   This is a young pup and very much in the critical window of socialization.  Now is the time to do something or return it before that window closes which is around 16 weeks of age.

Sorry I have to agree with JackieG. Boxers are very high energy dogs and can become a problem if they don't get the proper socialization and training early on.

OK Jackie G. I get it. I'm a newbie asking a legitimate question and I can read between the lines. Thank you for the useful weblinks. I've raised a lot of dogs in my years and this is not my first high needs puppy. I've had a worse puppy before, specifically, the one my ex husband brought home for me to raise years ago against my wishes. The puppy was only 5 weeks old. Need I even tell you how many behavioral issues I had to work on? Turned out to be the smartest and one of the most disciplined dogs I've ever owned hands down. So, when I ask for advice, that doesn't necessarily mean that I have no experience or sense about what dogs do or don't need. The fact that I even recognize the behavior as unacceptable should have given you a clue. Most people would have just slapped the dog and continued on with their day without a second thought. I asked my question on here with the hopes of some possibly useful advice to add to the advice I already received from my breeder friend who also works at a Vet clinic and has dogs she has been very active with  agility training. So, as far as your advice, I'll take the good and I thank you and I'll leave the judgments for the next person here asking the same question. And yes, if I have to, I will spend money for a trainer. Have a nice day and thanks for your time.

You're welcome.