So, you just bought a new pink winter blanket for your horse and you want to know if she likes it? Read on if you want to know more about whether or not horses see color.
To understand the answer, remember that a ROD is a light-sensitive cell in the retina that allows for side vision and the ability to see objects in dim light (night vision). A CONE is a light-sensitive cell in the retina that provides color vision and sharp central vision.
Most humans have what is called trichromatic vision, relating to the peak cones in the retina, while horses are dichromatic, having only two peak cones. This places them in a similar situation as humans who are “color blind.” However, as one with color blindness could relate, it is not so
“black and white” as a complete inability to see color or to distinguish red from green, the two most commonly experienced forms of color blindness in people. There is a great deal that goes into discerning color, such as hues, luminescence, relative textures and knowledge of the environment perceived in the brain.
Ultimately, humans with “normal” color vision see four basic unique hues: blue, green, yellow and red, along with 100 blends of these colors. Horses, like humans with red-green color deficiencies, have only two unique hues, which are believed to be blue and yellow, or something similar. So, it comes down to the ability to differentiate different colors from varying hues of gray.
Studies show that horses can differentiate blue and yellow from gray, but may have more difficulty with green and red. However, this deficiency has allowed for a benefit, in that horses have an increased sensitivity to light. This allows for better panoramic vision, and it is believed that, similar to humans with dichromatic color vision, horses can “break the camouflage” of certain colored objects, thus giving a survival advantage to the horse.
Below is an example of what a horse is likely to perceive in both color and clarity. (J Vis 1:80-87, 2001). So when you buy that fancy pink blanket for your horse, your horse may say, “Pink? Well, if you say so.”
Dr. McKee, is owner of Apple Valley Equine Mobile Veterinary Services, based in Hendersonville. She provides veterinary care to horses in the Henderson, Transylvania, Buncombe and Polk county areas. She is also a certified veterinary medical acupuncturist, treating both large and small animals. Dr. McKee lives in Hendersonville with her husband, Dr. Patrick McKee, and their two daughters, four dogs and three horses.
A-C photo pair captions: Horse as seen by horses. Horse as seen by humans.
B-D photo pair captions: Horses and humans as seen by horses. Horses and humans as seen by humans.