Black Dog Syndrome is a pretty simple effect noticed by employees at pet shelters. It has been studied many times, by people who knew what they were doing. But it turns out that the syndrome is less interesting from a scientific perspective than the studies themselves.
Black Dog Syndrome
Volunteers at pet shelters are generally not overjoyed at the arrival of a litter of black puppies, and they're even less happy at the arrival of a large black dog. Being bleeding-heart animal lovers, they don't have any objection to the dog itself. They're anticipating a long stay, or even euthanasia for the animal.
Among shelter employees, it's considered a truism that black dogs are notoriously hard to adopt out. The workers there have a nickname for the problem – Black Dog Syndrome. No matter how sweet-natured the animal, people see the dark coat and are hesitant to adopt the pet. For employees, who have to deal with the emotional difficulty of staying with an animal being stuck at a shelter for months, or even putting it down, black dogs are always a source of potential pain.
The Evidence for Black Dog Syndrome
The syndrome became so notorious among shelter workers that different social and veterinary science organizations set out to study the problem. The results were depressing. In a study that noted all the black dogs going in and out of a Midwestern animal shelter for a year, researchers found that dark coat color was negatively associated with adoption. A 1998 study of over 1,400 dogs at a shelter found that black dogs were less likely to be adopted than yellow, white, or gray dogs. Even cats have a tough time getting adopted if they have black coats. A study in a Colorado shelter found that black cats were much less likely to be adopted, regardless of age or sex.
Trying to figure out why black dogs were so thoroughly spurned, scientists removed the practical element of adoptions and just asked people what they thought of dark-colored dogs. An online study showed people pictures of dogs that had been digitally manipulated to have dark coats or light coats. Dogs with light coats were thought to be more agreeable, conscientious, and emotionally stable. (Incidentally the study also investigated whether people trusted floppy-eared dogs or pointy-eared dogs. The floppy ears won the day.) Another photo study showed that black dogs and black cats were considered less adoptable than their lighter-colored counterparts. The people surveyed considered the lighter colors much more friendly.
Clearly, there is a problem. People fear black dogs, particularly large ones. Humane societies and animal shelters need to either encourage people to get their dark-colored dogs spayed and neutered – emphasizing that they won't be able to find homes for the puppies – or start a campaign to change people's perception of dark-colored dogs.
But What About This?
But wait a minute. Let's take a quick look at that study done in the Midwestern animal shelter. Yes, color was a factor when people adopted dogs, but how much of a difference did it make? First and foremost, people adopted purebred dogs, regardless of color. Then they started searching out dogs according to size – no one is keeping a Great Dane in a studio apartment. They adopted dogs depending on how young they were, and some people had an aversion to stray dogs. Only after all these factors came into play did people start choosing dogs based on color.
In fact, color bias might work in favor of black dogs. A Los Angeles shelter showed that, out of 30, 000 dogs that made their way through the system, black dogs were a little more likely to be adopted than other dogs. In a New York no-kill shelter, black dogs had a shorter stay before they were adopted than other dogs. One researcher examined the records of nearly 17,000 dogs at similar shelters in Oregon, and found that black dogs were adopted faster than other dogs. Even photo studies are not all bad for black dogs. When looking at pictures of poodles, black dogs are considered more friendly than white ones, and people loved black labs more than nearly any other dog.
Clearly, Black Dog Syndrome is trumped-up. Certainly some shelters have a problem adopting out black dogs, but others are more likely to adopt out black dogs than other dogs. Even when the bias exists, it's a small factor, coming far behind characteristics like age and size, and most importantly, breed. Many studies have shown this.
The Problem With Studies
This is the problem with experimental science. Studies are done under two assumptions – that a sample represents the whole, and that during the experiment that sample is doing what it always does. When we look at Black Dog Syndrome, it seems like a pretty simple idea to test. Animal shelters keep records. How hard can it be to go through them and see how often and how fast black dogs are adopted? And yet studies stack up proving and disproving the same idea. A sample taken from the Midwest shows a trend exactly opposite to one in Los Angeles. A sample taken one year looks different from a sample taken another year. The sample doesn't represent the whole, and there's wide variation in what a sample of any given group of people do in one situation or another.
Meanwhile, anyone who wants to prove that the bias does exist can put their hand on a good stack of literature to show that it does, and anyone who wants to prove that it doesn't exist can do the same. And we've seen, again and again, that they do. Chance variation in any study can be used to prove anyone's point. And the more people study an issue, the more times an occasional outlying study will pop up – the same way multiple strings of ten "heads" will show up if you flip a coin enough times.
The most infamous example of this is the anti-vaccine movement. Leaving aside the fraud that caused the initial furor about vaccines, if there are two studies that indicate vaccines might be unsafe, and ten that indicate they are safe, both sides have all the literature they need to make their point. The same thing happens in other circles. If there is one study that shows that ginger cures eczema, and ten that say it doesn't, guess which one a person who sells ginger will put up on a website?
It's not just proponents of woo who do this. Recently FDA established a registry and the US started passing laws in an attempt to keep drug companies from doing five studies, picking the one that indicates their drug might help with a condition, and only publishing that one. In general, the solution to this dilemma is deciding based on the preponderance of the evidence, but science is slow, effects can be subtle, and rounding up all the studies done on every subject of interest is a Herculean task. At some point, you have to trust a curator to sum up the evidence for you. And so with enough work, people can prove nearly anything.