"Dogs, and some color-blind people, are missing the red-green cones. Dogs can see yellow and blue, and a combination of those hues. This means they see a lot of the world as grayish-brown," Klein ...

Most dogs have brown eyes, but there are breeds with pale blue, speckled, golden, or hazel colored eyes. The rarest color of all is green. Dog eye color changes as they age. It often takes nine to 12 ...