Sensitivity to Light

The canine and feline visual systems are adapted for performance under low light conditions. These animals have large corneas and pupils to collect more light in dim light conditions. They also have a reflective structure at the back of the eye called the tapetum which reflects light back out of the eye. This way, the retina gets two chances to capture each photon of light. A cat’s tapetum reflects 130 times more light than the human eye. This is why we see the shiny dog and cat eyes in photographs and at night when headlights or other types of light enter the eyes. Cats can detect light that is 6 times dimmer than that which normal humans can detect. Dogs also detect much lower levels of light than humans (but not as low as cats).

Dogs and cats are also very sensitive to motion, especially when compared to an object that is not moving. Some dogs were shown to recognize a moving object at 800-900 meters. If the same object was stationary they only recognized it at 500 meters. People are also more sensitive to motion than to objects that are standing still.