We got a 2 yr old lab mix from the shelter about 6 months ago. She was very shy. She was very thin and also had a skin condition. The shelter was reluctant to let us have her because we already had an older male Papillon. They told us we could exchange her if things didn't work out.
After about 1 week of working with her, she is the sweetest, most loving dog I've ever had. She is back to her normal weight and the skin condition disappeared.
Please give the shelter a try!