"Different species have different kinds of a tapetum, which is the reflective layer under the retinal pigment epithelium. In some species (cats and dogs) it is in cells with zinc-rich rods that are spaced (from memory) half a wavelength of light apart. Cats have a big tapetum since they are nocturnal, and dogs a small one. Other species (sheep, cattle and horses) have an extracellular tapetum composed of collagen laid in orthogonal arrays. This gives rise to different reflective hues. Any disease in the overlying sensory or nonsensory retina will have an effect on the reflectivity of the tapetum. Increased reflectivity is one of the standard criteria for retinal atrophy in domestic animals.
The tapetum is an astonishing and intriguing biological structures to look at, especially with an electron microscope."
What kind of animal eye colors at night have you seen?
Deer appear white
Cats look green
Foxes have been red
Raccoons and possums have looked reddish green
Bigfoot reputably red
Chupacabras and werewolves are yellow.