3 yr old Rat terrier jack russell mix wont let us pick him up

Question
We just got a 3 yr old jack rat from a person that boards dogs and takes dogs in so she can give them a good home. This place seemed a bit ify to my fiance and me but the dogs all seemed really happy (judging from all the other dogs they had). She only had the one male and we both wanted him. She let him out so we could interact with him, he seemed really shy and timid around people and even around the other dogs. With that said, we got him home and set him in the kitchen to let him snoop around and get used to his surroundings. when we try to get close to him or try to pick him up, he seems to get scared and wont let us near him. we thought we'd just give it a little while since he is 3 and in a new home, but he just sits in the corner and is not happy when we try to pet him or anything. the weird part is, is that my fiance held him all the way home and he was a complete sweet heart. maybe we just need to give him time to adjust. we've tried feeding him, giving him water, even a treat; he dont eat or drink any water. Also, I think that maybe was abused or mistreated in some way. will this stuff pass or are there any tricks to getting him to warm up to us? this also makes me wonder if he is going to be ok around other people.

Answer
Hi Cullen,
How long have you had him home? If it is just a day or two then give it some time BUT you may have a very serious problem on your hands.  Call the place and get as much information on this dog as possible. You don't sound very confident or sufficiently knowledgeable to be able to handle this on your own. It may be the reason he was put up for adoption in the first place.
It is possible this will only worsen if you can't get a handle on it quickly or if you are extremely patient and get a behaviorist to work with you - then maybe you can turn this dog around with love and tenderness. As far as interacting with other people - he may take his cue from you. I would put a leash on him and let it drag alongside and if you want him to come to you then just pick up the leash and give him a treat for responding. As far his not eating he will when he gets hungry enough. Just keep trying but don't leave it there if he does not eat with in 15 minutes. Pick it up and try again later.
Terriers are extremely willful and stubborn. It takes a lot of positive reinforcement to change behavior but these dogs love to please or else they will dominate- positively or negatively. They want/need a pack leader. Give him a few days and be gentle to him. Don't overwhelm him. Let him come to you. Try getting down on his level and just be in the same space so you don't tower over him and he can relax.
good luck,