Aggressive Chihuahua Terrier

by Brittany
(Peoria, AZ, United States)

My dog's name is Zero. He is a Chihuahua Terrier mix. We found him over a year ago in our front yard and decided to take him in.

We think he is about 3 or 4 years old. And when we first got him, he was fine. He got along with the other dogs perfectly fine. When we had people come over he would bark at the door like the other dogs but then would stop once the others did. No harm done.

Then about a few months ago he started to get more aggressive. He's still fine with the other dogs in the house, but now when we take him to the dog park he barks and tries to bite stranger dogs. And now when people come over he keeps barking at them and bites at their ankles and knees.

There was no harm done until recently he bite one of our friends knees and broke skin.
We really don't know what happened and don't know what to do.

He is a really sweet dog to everyone in the house and to the other dogs in the house, its just when strangers come around he gets violent.

I really don't want to put him down or give him away. So if there is something I can do to fix this problem I would love that.

Thank you,
Brittany

P.S. He is neutered.