Think of it like this, if you were enjoying an ice cream cone and someone took it away you would probably not be too happy about it. Then, someone comes a second time, so you yell back (or in a dogs case growl) “hey, why are you taking my ice cream cone!”. Finally, the person comes back a third time, and knowing what has happened in the past, you may become reactive (or in a dogs case, bite).
Now, if that person were to trade $20 for the ice cream cone you may react differently and see the value in the trade. For your dog, instead of always taking something away from them try trading it out for something of high value to them such as a favorite toy or high value treat.
For more information, we recommend checking out Truly Force Free Animal Training’s Understanding Canine Body Language Webinar or Understanding & Helping Your Reactive Dog Webinar