Dogs are pretty smart, and every dog owner has wondered at some point whether their dog can recognize other members of its species. The not-so-surprising answer: yes, they definitely can!
Studies have shown that dogs do indeed recognize other dogs — even when they're on a computer screen. In one such study, two independent teams of researchers tested whether dogs could recognize pictures of other dogs when also presented with pictures of inanimate objects and humans. Both teams confirmed that their subjects could recognize other dogs, but some criticized the study for being too small (they restricted the experiment to 24 pictures per category).
One critic, Dominique Autier-Dérian from LEEC and National Veterinary School in Lyon, France, decided to put together a larger study to test these findings. He and his team chose nine dogs and exposed them to thousands of pictures of different dog breeds, as well as pictures of other animals (including humans and various wild and domestic species).
The team found that every dog successfully identified the other dogs in the photos.
Most dog owners probably aren't surprised by these findings. If you've ever walked a dog, you know that they react in a very specific way when they encounter another dog. However, the conclusions in both studies are notable. They suggest that dogs can recognize other dogs using vision alone. Dogs use their sense of smell as their primary mode of gathering information. So while it's not surprising that dogs can recognize other dogs by smell, it is somewhat surprising that they can do it using sight alone.
Also, there is incredible diversity among dog breeds. Size, color, coat texture, ear shape, and many other traits vary wildly among dogs. Still, dogs are able to identify other dogs, no matter how different they may look from one another.
The bottom line: dogs are really good at recognizing other dogs. So next time your dog greets another dog, give him a pat on the head for being so smart.