6 month old cocker showing aggression

Question
Hi,
I recently adopted a 6 month old cocker spaniel mix (think with golden retriever) puppy from a private party. I have had her for about three weeks and have had no problems. SHe came from a family that had three small children in the house and swear that she has never been aggrssive towards the children.Yesterday, my 10 year old son went to put the dogs leash on her when she was in the middle of chewing on a bone. The dog lashed out at him and showed her teeth and was trying to bite him. This was very surprising to me since she had never done this before. The same night my 4 year old was playing ball with the dog just fine. Than the dog found her bone and began to chew on it. Well my daughter was still in play mode and tried to grab the bone to throw it. The dog growled at her and snipped her arm. It wasnt bleeding just a cat stratch type of bit. Purple but no blood. My daughter was pretty scare too as I. I took the puppy told her no and put her in her crate for the night. the only other sign of agression that she has shown is barking at things such as other dogs or workers. My question to you is if she is too old to stop this. We started obedience training the other day and she was very responsive. She took to the clicker and a can of beans for negative behavior. I really want to keep her but am very afraid that she will snap one day at the children. Do you think it is just a food thing? How can I tell? And how can I show her that my kids are the "alpha dogs" and not her? I read your posts about getting in her face untils he looks away and other tips. I am doing those but I am concerned about the children getting down in her face. I also have a 2 year old who likes to snuggle with her. Can you please help? I am very worried about the aggressive disorder that I found out cockers have. Thanks so much.

Answer
Hi Sarah,
First I'd need to know what "bone" was she chewing on?

There are some dogs that simply can't be given bones and it's very specific and you either don't give them OR give them and leave the dog alone.

The barking isn't aggression and can be handled with training.

My guess is you gave her a "real bone"?  Has she ever shown any "possession-aggression" about anything else?  If not, the answer is simple.  No more bones.  Ask the previous owner if they ever gave her any.  If the answer is no, then that's it.

There's something about a real meat bone that triggers "prey mode" in the canine mind.  There are perfectly lovely dogs that just can't have bones.

So let's deal with that and then we can talk about getting her to understand the pack order :)
Delores