Hi, my dog (Muggs) is a 11 month old Yorkie Poo, and he will not stop barking and growlling at strangers and/or their pets. He has also begun biting and nipping. I have tried the shaker can method, the spray bottle and holding his muzzle shut and shouting OW, none of which stop thiss behaviour from returning. I was just wondering if anyone had any suggestions on how to fix this problem, I mean its hard to take him out. And this has really just begun, about a month or two ago...

I copied the following from this web site.

My aunt also has a website with a lot of information on raising Yorkies (not Yorkie Poos but I assume it may still be helpful.) at desertroseyorkies.us. She doesn't sell them anymore, but there's some good info still on the site.

What You Can Do:

• Seek professional advice. An aggression problem will not go away by itself. Working with aggression problems requires in-home help from an animal behavior specialist.
  
  
• Take precautions. Your first priority is to keep people and other animals safe. Supervise, confine, and/or restrict your dog's activities until you can obtain professional guidance. You are liable for your dog's behavior. If you must take your dog out in public, consider a cage-type muzzle as a temporary precaution, and remember that some dogs are clever enough to get a muzzle off.
  
  
• Avoid exposing your dog to situations where he is more likely to show aggression. You may need to keep him confined to a safe room and limit his contact with people.
  
  
• If your dog is possessive of toys or treats, or territorial in certain locations, prevent access and you'll prevent the problem. In an emergency, bribe him with something better than what he has. For example, if he steals your shoe, trade him the shoe for a piece of chicken.
  
  
• Spay or neuter your dog. Intact dogs are more likely to display dominance, territorial, and protective aggressive behavior.
  
  

What NOT to Do:

Punishment won't help and, in fact, will often make the problem worse. If the aggression is motivated by fear, punishment will make your dog more fearful, and therefore more aggressive. Attempting to punish or dominate a dominantly aggressive dog may actually lead him to escalate his behavior to retain his dominant position. This is likely to result in a bite or a severe attack. Punishing territorial, possessive, or protective aggression is likely to elicit additional defensive aggression.