You need to get him out of the dog park first of all. It’s a horrible place to take a dog that has aggressive tendencies. Ed has written an article about them.
There is no such thing as a love nip. Your dog is over stimulated and redirecting the excitement/aggression at you. This needs to be addressed for what it is, lack of respect and aggression. You should take this very seriously especially since he’s fixated on and has bitten a child. This is an accident waiting to happen. Here is a section on preventing dog bites in kids. Take a look at some of the photos of what can happen to kids when unmanaged dogs make the wrong choices.
A child could be badly injured and you could be sued. Depending on the laws in your state, your dog could also be put down. If I had to guess, the people you got him from rehomed him because they had incidents with their child.
This dog should be on leash, supervised and trained. If he’s putting his mouth on you in the way you describe it’s a bite and he doesn’t respect your authority. That is what Taz is communicating to you. Lack of respect.
Start with our groundwork program and Pack Structure for the Family Pet. I’d also recommend Dealing with Dominant & Aggressive Dogs.
Please train him and change the way you are handling him before something worse happens. I don’t think you understand how serious this is. You may also need a muzzle. We have directions on how to measure the dog for a muzzle on this page. Dogs like this sometimes act out more aggressively when you suddenly start demanding respect, so you need to be prepared for this.
We also have a number of eBooks, which include topics that may help you.
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