Recently, a man was killed by the dog he had just adopted from the local shelter that day. The dog had been picked up as a stray and held at the shelter for 5 days before being placed for adoption.
The local paper reports:
"Tedford said the [dog] showed no signs of aggression while at Rabies Control and she had not heard of it biting any Rabies Control officers. Officers handle the dogs while they are at Rabies Control and look for signs of aggression such as growling, showing teeth and lunging, she said.
'We by no means would adopt an animal out that showed any signs of aggression...'"
Here's the problem, not all dogs growl, lunge, or display their teeth before an attack.
Now, there are a lot of reasons that aggressive behavior wasn't observed in this dog while at the shelter.
The employees may have been skilled enough in their interactions with the dog that they never provoked any aggressive behavior.
The dog could have been under enough stress while in the kennels that he wasn't exhibiting much of any behavior at all.
There may have been something about the victim's interaction with the dog that inadvertently provoked an extreme response.
If the dog had previously been punished for aggressive displays, those warnings might be suppressed.
If the dog's behavior was predatory, he wouldn't have given a warning sign, at all. Predatory behavior is fast and silent, which is what makes it so dangerous. Lions don't warn zebras before they attack.
So, while we can't know exactly what happened with this particular dog, we can say this:
A lack of aggression is not an indication of safety. This is why behavior professionals see a lack of friendly behavior as important information.
"Friendly" dogs are NOT subtle in their affections. They lean up against you, they paw at you, they even shove their muzzle under your hand, spilling red wine on your new beige couch (personal experience).
Even my Border Collie, who is admittedly much more subtle than the wine-spiller dog, curves his body and leans into me when he seeks affection. A dog that is uncomfortable avoids contact with all but the tip of their nose, if that.
The more a dog seeks out close contact (petting, hugging, and overall handling), the more tolerant they are of humans, in general. More tolerance = less risk.
If this shelter had the funding for a well-trained behavior department, could they have spotted something that was an indication of the dog's potential? Possibly. Could a basic temperament test have raised red flags? Maybe. We will never know in this case.
I'm in no way blaming the shelter. Most municipal shelters are overflowing with animals, underfunded, and understaffed.
I'm not saying that all dogs that show a lack of friendly behavior are going to kill you the minute your back is turned. They could be fearful. They could choose avoidance over aggression.
However, I am saying that it is noteworthy.
We can't prevent future bites and fatal attacks with a dog park or reality show-level of dog behavior knowledge. Some of the most dangerous dogs are the ones that don't look aggressive to the general public.
The lack of aggression is never, on its own, the sole indication of a safe dog.