There is no quick and easy answer for this aside from you may have to work with him over several months to rebuild his confidence. . It’s not gong to be easy since this is a learned behavior and something apparently in his past that scared him severely. it’s a matter of confidence building skills and many many repetitions and confidence building skills over the next few months. I wish I could say something like you could teach him in a day or two or even a week or two but you may be working with him for several months before you see a great
If he’s a good boy and gets a lot of praises the start of something simple like the down stay while laying at your feet in front of you and them every couple days moving back a few feet until you see him on other side of the room comfortably in the down stay, later on he does it In another room but still within your site, eventually you’re able close the door for periods of 30 to 45 seconds practicing until after 2 to 3 minutes then later 5 to 7 minutes adding a minute of time daily. If he starts getting anxious when you move ahead, simply repeat the last lesson he was comfortable with until he feels secure again. The minutes will soon turn into an hour that he knows nothings going to happen when you’re not touching him at the site. After the hour then you can add 5 minute increments.
I’ve had several dogs come to me after being traumatized and they are clinging for me as they are are so fearful that they do not function outside of their small plastic kennel they have spent months to years in. it takes weeks to diet them out and like a human touch again. In the end you’ll find it’s well worth it because you’ll have a very loving very well-adjusted dog absolutely idolizes you and will do anything for you or your family.
Try not to get frustrated when you’re working with him because it’s not his fault nor is it yours sometimes just having an unstable temperament being poorly bred while others have not been socialized every bit fearful of anything strange new or different such as loud noises of crowds of people and give Them lots of praise and indirect expose before they’re not as afraid and it’s up to you to work with him and teach him. We work with dogs that are afraid of groups of people by simply people watching for an hour a day starting a block away at first and moving up one yard closer per day or every other day. Then when the dogs not showing signs of stress we walk on opposite side of street as the park working our way up to the park side.
Good luck with your pup, he is worth all the work you will be putting in with him. Remember to keep his lessons short, but repeat them many times during the day when you have a few extra minutes. Dogs seem to learn and retain better in shorter lessons held more often. It helps set his training up to be successful, and remember to end lessons on a good note, that’s also a confidence builder.
Also ask the behaviorlist about teaching you the cradle and hold, it’s a move that helps the dog feel safer and more secure and does help build up his confidence.