Have you heard the one about how you should never feed a barking dog, as that will reinforce his bad behavior? If the dog is showing fearful body language while barking, ASPCA behavior experts recommend giving the following a try. (Note: These steps can be very beneficial for the fearful barker. They should not be used for the confident pup barking for your attention.)
Approach the fearful dog in his kennel as a potential adopter would, by walking straight up to him. (If this is too much for him at first, try a less direct approach: sideways, crouching, averting your eyes)
Toss him a soft, yummy treat
Repeat multiple times, a few times a day
If this technique is helping, try putting a treat bucket on the outside of the dog’s kennel so that others can teach him that people approaching means great things. (If the barking increases in frequency, this is not the correct technique for this particular dog.) He will soon realize that the person approaching is not a threat—they’re bringing delicious snacks, after all—and he will likely lose his motivation to bark.