As with a stray, if the dog hasn't begun to show a friendly interest in shelter staff within 7 days, it's not likely to be a good adoption candidate. It goes without saying that no Chow with a bite record or history of aggressive behavior toward people should be offered for adoption no matter how good his temperament appears to be. In over 10 years of working with abandoned Chows, I've never been bitten by one and rarely need to use a muzzle. My success comes from using good safety practices and common sense. Anyone can learn these simple tricks and they apply to other breeds as well as Chows.
Chows are very perceptive and quickly pick up on people's emotions.
They are especially leery of people who dislike or are afraid of them. They may behave aggressively or erractically toward such people. Chows are often remarkably docile, friendly and respectful of people who aren't afraid of them. Pretend he isn't even there and go about your business as usual. Do not make direct eye contact or try to pet him.