Biting strangers

Question
Hi. we have a 5 year old JR, male. We also have 2 stray dogs which we got about 2 years ago. The JR is the dominant one of course. The JR has bitten a few strangers when they have tried to pet him (when he was on a leash mostly) and now we are very cautious and usually try to warn people not to touch him. I started working 2 months ago and we hired a dogwalker to take all 3 out at lunch time for 30 minutes. This worked for 2 months but the dogwalker moved away and we had to find another. She started this week. When walking with them on a lease, the JR jumped at a stranger walking past (he did not try to pet them or even stop to speak to her) and bit his leg. Then when they came home, he did the same thing with our neighbour who also was just walking past. He has never done this before (ie, lunging at people). It is difficult to control because the behaviour is so unpredictable. I will buy him a muzzle today but I noticed in general his behaviour has deteriorated in the past few months (he fights with other dogs viciously in the dog park), and growls at my kids more and at me although that doesn't bother me because he knows I am the dominant one and always backs down. We will probably be moving again in about 1 year and I am starting to think this problem will only get worse. He needs a stable home with outside living. Should we consider to rehome him or do you think this is a temporary problem due to change. How can I teach him not to attack people apart from yelling at him after the fact (which makes me look like a mad woman). The other problem is that the 2 strays who are like lambs are copying him and also attacking now the other dogs and barking...HELP!!

Answer
Hello Lisa,

I think he has gone beyond the stage that you can help him on your own. It's time to get a professional dog trainer involved who is adept in matters of aggression. I think the first thing they will say is that the dog needs much more exercise than he is getting. As you know Jack Russells have much energy to burn and when it is not released, they tend to act out, usually in a negative manner such as the nipping and biting. He is probably very frustrated with the change in dog walker too, as well as you going off to work. Those are a lot of changes for a dog (any dog) that thrives on routine. Do you have a treadmill at home? If you aren't able to take him out first thing in the morning for a robust and energy draining walk/run/play, then the next best thing is to put him on that treadmill for a good half hour and help release some of that pent up energy. I think you will see a remarkable change in his temperament right away.
When walking him, make sure the walker is not fearful because the dog can sense it right away. Have the dog walker completely turn around and go the other way (towards home)when he begins to lunge toward another dog or person.  There is also a method of training with food that takes the dogs mind off people and dogs coming toward him that makes him focus on you and the food instead of the approaching people. It's important to do it correctly though because you don't want him to think you are rewarding him for being aggressive. A professional dog trainer should help you and your whole family with this. Biting and nipping family members can not be tolerated and he needs to re-learn the pecking order in the house and that he is bottom of the totem pole! I hope this helps at least a little bit, it's hard to get into much detail on this forum. I don't think you need to rehome him at all, he just needs to burn some energy and get some refresher training done! GOOD LUCK!!