Bentley, a Jack Russell, was rescued at 8 weeks old. When someone leaves my house, he races to the door and jumps against it, barking. If I go out with someone, he goes to the door agressively, like to bite or nip. He has nipped someone before. I now either crate him prior to someone coming or lock him in another room. This behavior isn't any different with people he knows or strangers. What do I do?
Putting Bentley in a separate room or a crate is a good start — you don't want him to keep rehearsing this behavior until you've taught him what is appropriate. You'll want to work on training at low-excitement times when there aren't a lot of distractions. First, set up a dog bed across the room where Bentley can have a nice long-lasting treat — a frozen kong, a safe bone or chew toy that he really likes. Be careful Bentley doesn't see you get the goodie (this is the hardest part). Then, call Bentley to that spot and give him the goodie. Praise him when he engages with it. Do this several times a day for a few days, until just calling him to you when you're near this spot means he runs over and jumps on his bed. You're ready for the next step. Walk over to the front door, touch the doorknob, then call him over and give him a treat on his bed. Have several people practice this with him repeatedly until Bentley starts to head for the bed as soon as he sees someone touch the door. Then, start leaving a goodie on the bed in advance, and rehearse by opening the door just a foot or two, then closing it again and praising him while he's chewing on his goodie. He'll need continued practice, but you've successfully taught him to send himself to the other side of the room when someone goes to the door.
This week's expert is Amie Glasgow, a behavior and training coordinator at the Maryland SPCA (mdspca.org). Submit your questions to firstname.lastname@example.org.