Sudden aggressiveness

Question
I walk my 18 month boxer daily for approximately 1 hour. Usulally half way, he'll turn on me without notice. He jumps and mouths my arms. It's as if something has come over him. I usually have him sit, walk away 20 feet, and wait a few minutes. It works for a few minutes and then he continues. I've had the problem for 9 months. He's fixed. He sometimes behaves the same way in the house. I tie him up and that usually settles him. Recently I used some force and shook him, but that didn't work. I also use treats and that works sometimes. Nevertheless, it's annoying and stressful. Do you have any suggestions?

Answer
A one hour walk is too long. He is tired and wanting to go home, and is being aggressive to let you know he is displeased.

As far as his mouthing your arms, jumping on you, and you "shaking" him- this is not the way to discipline, and his behavior is not acceptable.

You needed to begin with what is acceptable behavior and what is not when he was 2-3 months old.

Do not shake him, do not tie him up- he does not know why you are doing this because it is not disciplining at the time of the behavior ....

You need to establish you are the "alpha" not him. You cannot shout, yell, raise your voice, and holler at him, or even "talk." This is useless because he does not know your language and your excited mind only agitates his excitement.

Please take the time to watch Cesar Millan's Dog Whisper on National Geographic Channel and buy his books.

He recommends you keeping calm and assertive and use as little talking as possible.

A simple stern "no" and make him submissive, Push him down into a lying position which is a submissive position.

To show him you are the alpha, try this trick for 2 weeks.

At feeding time (don't self-feed in these 2 weeks) put his food bowl on the table where he can see it, make him sit and watch you quietly. Place a cookie or cracker on the table behind his food bowl.

Pick up the cookie or cracker, it will look as if it came out of his food bowl, and stand and eat it without looking at him.

When you are finished, tell him to eat and place his food bowl on the floor in front of him.

This is giving him permission to eat AFTER you ate. In packs; wild dogs, wolves, etc., the alpha always eats first and all he wants while the pack waits for the left overs and permission from the alpha, to eat.

2 weeks of this proves you are the alpha, and he is not.

Then, the rest of his behavior should improve because he now knows he is not an alpha-- you are, and he will await your instruction and commands.

Also, practice walking him for 15-20 minutes max only allowing him to walk on your left (if you are right handed) and stop dead in your tracks tightening his lease by shortening it firmly, (no yanking) and wait. He should sit. Then proceed and if he pulls on the leash trying to lead you, walks in front or behind you, or moves to your left-- stop each time. Make him walk beside you and on your left and you do the leading- he is to follow your instruction, walk beside you, stop when you stop, await for you to tell him what and when.

When he jumps up on you, immediately push him down into the submission position and wait.

Practice, practice, practice.  Be sure to watch the Dog Whisper. You can also watch it on hulu.com, and on the National Geographic Channel on your computer.