[Babbie]

I got very curious about this and decided to start a personal research So far here is what i found:

From site: http://www.vin.com
The quality of reflected light seen varies with the breed and coat color type of the animal; animals with a tapetum will have a bright fundus reflection of yellow, orange, or green, while those without a tapetum usually have a red fundus reflection (produced by the choroidal vessels). Regardless of the color, the fundus reflex should be uniform throughout the pupil, and be free of aberrations. By examining the fundus reflex, the clinician can accurately estimate the amount of light reaching the retina, and thereby estimate the quality of sight. For example, in an animal presented with the complaint of blindness suspected to be due to cataracts, which has a reasonably normal fundus reflex, blindness cannot be attributed to lens opacification. The same principle applies to opacification anywhere within the eye, including the cornea, anterior chamber, lens, and vitreous. Once an opacity has been identified, it is examined in more detail using other techniques.
P.S. Tapedum is the reflective substance within the dog's eye.

Site: http://www.vetmed.ufl.edu/
The size of the pupils are evaluated and the direct and consensual pupillary light reflexes are tested. This should be done with a bright light in a dimly lit room. The pupillary light reflexes are affected by the psychic state of the animal, room illumination, age, many topical and systemic drugs and the intensity of the light stimulus. Older animals may exhibit slow and incomplete pupillary light reflexes resulting from atrophy of the iris sphincter muscle. This is common in small dogs, especially poodles. The pupillary margin may have an irregular or scalloped appearance. Incomplete iris atrophy may give an irregular pupil shape.

When speaking with my breeder’s vet he explained the following:
The Tapetum Lucidum reflects all the light that passes the retina to the end of the eye and then back…so it will reflect 2 times (going in and going out). There is cases that this light reflected by the tapetum is not reflected in by the retina and it is just reflected out by the pupil…the tapedum is a shiny membrane that may have different color like green, blue, yellow and even white.
When the eye reflects red, what may happen is that this animal doesn’t show this membrane (tapedum lucidum) or has some deficiency in it. Cats, for example, don’t have this membrane.