The images are real images allowed by petfinder. It is people that have taken
a picture of their animal for adoption.
If you choose the wrong picture, it lets you know that you did and you can click
again.
For the most part, it's rather easy to distinguish a cat from a dog. If you can't, you
might want to look into getting a larger monitor or increasing the screen size resolution.
Also,many computers allow you to change the size from normal to large.