Our world about us is so filled with color that it is hard to believe that dogs cannot see colors, at least by human standards.  What dogs probably do see is the world in black and white and many shades of gray—much like what you see when you watch a color television program on an ordinary black-and-white TV screen.

Cats, mice, horses and cattle cannot tell one color from another, and neither can deer or most other wild animals active at night.  During the evening, when the world is a shadowy, colorless place, the ability to see colors is not important for survival. – Dick Rogers