Also to know is, what color dogs are least likely to be adopted?
For years, there's been concern in the shelter and veterinary community that black dogs were less likely to be adopted. Recently, a large U.S. study showed no evidence for this so-called “black dog syndrome.” This is great news to me personally and will help in ways you might not consider at first.
Hereof, why are black animals not adopted?
While there is no clear rationale, there are theories as to why black dogs and cats are harder to adopt. They do not photograph as well as lighter colored animals, and their features get lost and don't translate well in photos, making them hard to market to a discriminating and – at times – discriminatory public.
Those dogs just don't get adopted. If your dog doesn't get adopted within its 72 hours and the shelter is full, it will be destroyed. If the shelter isn't full and your dog is good enough, and of a desirable enough breed, it may get a stay of execution, though not for long.