Umm... I guess I'm missing something... Daisy is your & Shaun's dog... why are you dumping her off with some one else at the drop of a hat?

If this is such a sudden and shocking incident, then why are you acting like Daisy is a lethal dog? Ok, so she left a blister. I'm sure you are aware of the damage that a dog CAN EASILY DO, with very little effort. They have big, sharp teeth. What Daisy did is not right, but I would consider it a nip. When several dogs are all rushing to greet a "new" person (even if the dogs have known her forever, she is not one of the pack, at least not now), they can get excitable, and they can get confused, and they can do stupid things. EVERY dog on the planet CAN bite; it just depends on the individual's level of tolerance, or of stimulus, or of fear, or of pain, etc. I do not allow either of my dogs to barrel up to people coming into the house and jump all over them - that is just rude to the person visiting, and pretty dangerous, especially when you have several large dogs.

Now that you know Daisy is so excitable, and has a tendency to become defensive, why can't you even try to manage the behaviors? Even try contacting a behaviorist? I just cannot imagine giving up on either of my dogs like that, and I would never believe you would, either. You have SO many options to nip this in the bud!

http://www.animalbehaviorassociates....or_chaos_1.pdf