Color Blindness in Dogs
It is no secret that dogs have heightened senses relative to humans: their abilities to smell odors that we would consider imperceptible; to detect small movements that we cannot see; and to hear frequencies undetectable to our ears are nothing short of amazing. However, humans have an advantage over dogs in that most people can see a full spectrum of colors while canines only have limited abilities to see in color. The differences in the dog and human eye are discussed.
Dog vs. Human Eye The human eye is well understood by scientists, and we know that the ability to discern different colors (such as red and green) is thanks to the abundance of specific cones, or photoreceptors, in the eye’s retina. From the 1930’s to 1960’s there was a widely held, but unstudied, belief that humans and primates were the only members of the animal kingdom that could view the world in color and that the rest were limited to seeing shades of black and white. Recently, however, scientists have further studied the eyes of dogs (and other animals) to better determine exactly what they are capable of seeing. Whereas humans are trichromatic, meaning they have three types of cones in their retinas, dogs are dichromatic.
Why are Dogs and Humans Different? The overwhelming hypothesis is that dogs and humans have differing sight capabilities because of evolution and need. Ancestral humans primarily hunted during the day, making the ability to perceive slight changes in color necessary. Dogs, on the other hand, can hunt nocturnally (at night). Because of this ability, their eyes have developed superior night vision capabilities and can sense quick movements, as opposed to slight color variations. Whereas dogs have a larger lens and corneal surface in order to be adept night-hunters, humans required additional variations of rods and cones within their retinas.
What can Dogs See? What does this mean for your dog? Due to the dichromatic cone structure, dogs have vision similar to a human with red-green color blindness. Dogs can see varying shades of grey, as well as yellows and blues. If you are interested in seeing the world through your dog’s eyes, apps are available (such as Dog Vision) that gives an owner a greater idea of what a dog can – and cannot – perceive.
How Can a Dog Owner Use this Information? When picking out toys or objects for your dog, stick to colors that you know your pet can differentiate, such as bright yellow or blue. Toys that are green, red, or a varying shade will be difficult for your pet to locate in the grass, leading to frustration for both you and your dog. If training your pet to use an electric fence, avoid using boundary markers that are orange, as your pup will not be able to discern them. Instead, opt for blue flags, which are readily available. Ultimately, understanding and working with your pet’s abilities can create a happier and more harmonious household.