Blue Reflex

Dogs have a special reflective layer in the 

back of the eye termed the tapetum, which 

enhances nocturnal vision. Light passes 

through the animal's retina from outside 

of the eye and is then reflected back through 

the retina a second time from the reflective 

tapetal layer beneath the retina. This double 

stimulation of the retina helps these species 

to see better than humans do in dim light 

situations.  The color of this tapetal layer 

varies to some extent with an animal's coat 

color. A black Labrador retriever, for 

example, will usually have a green tapetal 

reflection. A buff Cocker spaniel will generally 

show a yellow tapetal reflection. Most dogs 

have a blue tapetal reflection.