Yuku free message boards

I have a 5 month old dominant female lab/retriever cross who exhibits aggressive behavior. She emits low growls and snarls if she doesn't get her own way. She has bitten hard enough to break the skin several times. When she is good she is very sweet. We cannot have her off leash as she is too wild and destructive. We are attending obedience school and I have been told I am a "soft" handler and the dog needs a tougher handler. I am trying my best - I do love this little dog - but I was also told by the trainer that this dog should never be left unattended with small children. Is there any hope in training this dog to stay with us and to listen to more than one person? We live in the country and all of our dogs have had freedom to roam our property - I hate to have to lock this one up in a kennel. She is very smart but seems to want to obey only if there is a reward or if it suits her. I am almost ready to give up on her but it is VERY hard to. Can you help me?