The US Open Tennis Tournament is in full swing at the Arthur Ashe Stadium in Flushing, Queens and, over the next two weeks, New York City will be all about tennis. For some dogs, every day is about tennis—tennis balls, more specifically. What is it about tennis balls that makes them so popular with dogs? Their yellow-green color might help answer that question.

Dogs See Yellow and Blue

The common misconception is that dogs are color blind and see only in shades of gray. However, the truth is dog’s eyes have receptors for blue and yellow. This means their vision is similar to a human with red-green color blindness who sees blue and yellow quite well. Below are two color wheels. On the left is the color wheel of a human with normal vision. On the right is a color wheel of a human with red-green color blindness. This is similar to the colors dogs see. A bright yellow tennis ball fits right into the second color spectrum.

Dog Eyes are Designed to Detect Movement

Human eyes are positioned in the front of our heads, giving us good forward vision but less peripheral vision than dogs, who have their eyes placed more to the side. This feature gives dogs great peripheral vision and a wider field of view to see those tennis balls you are throwing for them.

Dogs also have higher visual processing speed than humans, i.e. a higher “frame rate.” Frame rate is the number of still images needed per second for the brain to interpret them as a moving image. Dogs have a frame rate around 70 frames per second, while humans are around 20 frames per second. Dogs’ high frame rate helps them detect a fast-moving object, like a tennis ball.

Even though your dog loves to play with tennis balls, they are not always a love match. Read a previous blogpost to learn the dangers tennis balls present to your dog.

To learn more about your dog’s eyes, read our Pet Health Library entries on cataracts, dry eye and glaucoma.