Taylor's now 4 months old. He's not an aggressive breed, beagle/poodle mix. He is good 85% of the time, but I have been noticing aggressive behavior in him lately. This behavior comes when he really wants something really bad. The other day, he found a chicken bone while we were taking a walk. I tried grabbing it from his mouth while saying, "No, drop it," and he lashed out at me. Thankfully, he didn't get my hand because I was holding him by the scuff. He did this again when he tried to pick up a half eaten peach from the ground. He is mostly fine when I ask him to drop paper/tissue/whatever else is on the ground. Please note, he is not aggressive over his food. I am able to reach in and pet him while he's eating at home. He is currently attending a puppy class. Yesterday (week 2 of training), while I went to go use the ladies room at a pet store, he bit our trainer and actually broke skin! (Maybe this is a separation anxiety issue...). Anyways, we tried to teach him "leave it" with some toys and food. He went on growling and tried attacking my hand. My trainer did not look happy and asked me to work this at home. Finally, at home, sometimes he would nip, growl, bark, and run like crazy man. I tried ignoring him...and sometimes it works. When I try to calm him down by asking him to sit, he runs away without doing the command. Please help.... I am so discouraged that my trainer "sounded" like it was a lose/lose situation!