Written by Staff Veterinarian
Although it is difficult to know for sure, there are actually many clues that can help us piece together how dogs and cats view the world. The most significant difference in our eyes compared to our pets is in the structure of the retina. The retina is a layer of tissue at the back of the eye that is responsible for transforming light entering the eye into electric signals that are then sent to the brain for vision processing.
The cells that make up the retina have been carefully examined and results have given us some interesting insight into the lives of our furry friends. For example, the human retina is structured to pick up a rainbow of colors and allows us to appreciate intricate detail. Dog and cat retinas are structured more for detecting the slightest movement and operating in low light conditions. These differences are a reflection of the way our ancestors hunted and survived in the wild.
Dogs do have some degree of color vision. However, they do not experience the wide range of colors appreciated by humans, other primates and birds. Based on the composition of their retinal cells, it is thought that dogs most likely see ‘colors’ with a palette made up of different shades of blue and yellow. Objects that we would view as red or green are seen as varying shades of gray. Cats also have the capacity for limited color vision. Based on the cells in their retinas, cat color vision may actually be a bit better compared to dogs. Despite this lack of a complete color palette, pets are able to detect subtle difference in shades of gray that would be indistinguishable to their owners. They also rely on their highly developed senses of hearing and smell to navigate and differentiate between objects.
Enhanced night vision is due to special adaptive features of our pets’ eyes. One of these is a structure called the tapetum lucidum. This is a layer of reflective tissue at the back of the eye that results in the ‘eye shine’ you may have observed in a photograph or in the beam of a flashlight at night. The tapetum causes light to be reflected internally within the eye, allowing more efficient use of small amounts of light. Also, synapses in their retinas are arranged so that very little light is required to form an image. However, there is a trade-off. These same features that allow for better night vision result in worsened visual acuity, producing a more ‘grainy’ image with poorer detail compared to humans.