What is "black dog syndrome"

n. A disputed phenomenon in which black dogs tend to be passed over for adoption in favor of lighter-colored animals, perhaps because of superstition or the belief that they are more aggressive.

Black dog syndrome or big black dog syndrome is a disputed phenomenon in which black dogs are passed over for adoption in favor of lighter-colored animals. Animal shelters often use the term BBD, or big black dog, to describe the type of larger dark-colored mixed-breed said to be typically passed over by adopters.