Aggressive Shepherd Mix

by Kelly
(NY)

My Dog Is Aggressive. We have a one year old German shepherd mix we got from the local SPCA about 6 months ago. We also have an 8 month old female Labrador we got at the same time. We've had both dogs approximately 6 months.

Our Shepherd mix has just recently displayed aggressive behavior. He will be seemingly normal but then become "moody." It can happen while petting him or correcting him. Out of the blue he will start to quiver his lips with a growl and then follow up with a snap. Normally we try to reprimand him verbally, but it doesn't seem to have any effect.

This morning his was chewing on something (carpet) he was not supposed to. I gave him a "no" command and told him to move. When I got closer he began growling and actually lunged at me. I aggressively hit him down (first time) and scolded him loudly with "NO! BAD DOG!" He began to run away, I followed and continued to scold. When he got to a point he felt cornered (I think) he turned around and growled again. I again scolded loudly, "NO!" He continued to search for a place to hide/be alone.

What do we do? 90% of the time he is a very good pet. He knows how to sit, come, and stay, even around food. But 10% of the time we don't know what to expect. He doesn't like being corrected or made to do anything against his will.