I'm at a loss as what to do with my Labrador/Dalmation mix, Starbucks. He's 5 years old and has been returned to the our shelter twice for biting people. He was biting cleaners who entered his kennel at the shelter, so I took him home to foster to try and work with him one on one. But I'm not making much progress and I'm afraid he might be getting worse. He's described as protective, and some of his aggression issues seem to stem from trying to be protective. I've taken steps to try and ensure that he does not feel a need to be protective of my house. I don't let him have full run of the house, and he's crated when I'm at work (this is also for the protection of my cats). When he's outside, I call him back in at the first sign of barking. I don't have any visitors over to my house though, so it's difficult to work with him here. In the car he used to go crazy whenever he'd see someone on the street, and start barking and growling through the glass. Now I've learned to watch him and as soon as he sees someone, or right before he sees someone, I start singing "happy people" and point towards the people and he doesn't do anything and I give him a treat after we've drove past. If he beats me to it though, I tell him "no", make him sit and no treats are given. He doesn't bark at people in the car as much any more. So the main problem I'm having is at the shelter. He goes to the shelter twice a week to attend adoption events. He knows most of the volunteers and is fine with them. He doesn't know the people visiting the shelter, and will growl and bark at them through his crate. Outside of his crate, it's hit or miss whether he'll behave or not with them. The other day I had him outside, Starbucks was sitting by my side, and I was talking to a guy who was interested in him (but who I didn't think was a good match for Star). Starbucks took a treat from him, but a few minutes later Starbucks jumped up and lunged for the guy. I didn't see it coming at all. I had a hold of Starbuck's leash and was able to pull him down before he made contact. Then yesterday the same thing happened in a different situation. I was sitting down in the office waiting to leave with Starbucks on my right. There was a person sitting to my left. Starbucks moved in front of me and the lady asked if she could pet Starbucks. He seemed to be doing okay, so I said yes. She pet him for a minute, and then she stopped. A few seconds later Star lunged and grabbed the sleeve of her coat. I don't really know what to do. Starbucks is the smartest dog I've ever fostered. He knows a lot of obedience commands. I've started working on clicker training him and he's picking that up fast. We're attempting to use positive training methods with him. But I don't know what to do to get him over his aggression. I don't think he's afraid of strangers, which was the case with my last foster; I think he's protective of his crate, and protective of me, and aggressive towards anyone he doesn't know that gets too close. I'm open to any suggestions.