Agressive dog

[Pele's~girl]

Hi, I'm new and I joined specifically because I really need help with my friend's dog.

Her name is Brandy, and she's a mix breed who they rescued from a shelter less than a year ago. She's about two years old, and before she was adopted by my friends, she and her sister, Spirit, were badly abused. We don't know how, but it HAS affected Brandy's mind set.

Initially, Brandy hated me. Now, however, she and I are good buddies, but she continues to bark, snarl, and sometimes lunge at strangers who so much as approach the gate at their house. Spirit is not a huge issue, but she does get riled up by Brandy when her sister goes crazy.

So far, Brandy has not been labeled a dangerous dog, but she has bitten two people--including my stepfather, which is the reason I'm posting this. I don't want anything bad to happen to her, but I also care about my friends and my family too.

They all turned to me for answers but...I don't know anything! I'm the last person they should be asking. A few years ago, we lost two of our dogs because I was a stupid owner who let my dogs get out of control and hurt people. I don't want that to happen to my friends and Brandy.

Can anyone give me some advice to pass along?