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Pet Health Watch with Dr. Main
What Do Pets Actually See?
O
ften pet owners inquire as to whether their pets see
in black and white or color. Cone photoreceptors
are responsible for color vision in all species. The richness
of color and the number of shades are determined by
the number cone populations at the back of the eye. In
humans there are three sets of cones hence the term
trichromatic. People have peak absorbance in the red
green and blue wavelengths which are considered their
primary colors.
Since they are not predators, they
sacrifice binocular vision for their
own protection.
Pets are able to watch television
however it is less perfect than it is
for humans. In pets the response
rate of the cones in the retina is
slower than in people. Pets have a
difficult time fusing the television
images into a continuous image. For pets the images are
flickering rather than continuous.
Dogs and cats are dichromatic meaning they have two
cone populations. Answering the above question, yes
our pets do see color! Domestic animals absorb the blue
wavelength the best but not the green and red. Therefore
dogs and cats do see color but not as rich as we see color.
Interestingly humans are not at the top of the color vision
scale. Certain fish and birds are tetrachromatic, meaning
they have a fourth set of cones. These species are able to
absorb light in the ultraviolet spectrum giving them color
vision significantly richer than humans.
As for night vision it is true that pets have better night
vision than humans. In fact, in cats their night vision is six
times more sensitive than people. Cats are superior due to
their larger cornea and pupil, and the increased number of
photoreceptors at the periphery of the retina.
Lastly, we will look at visual acuity in dogs and cats. In
general image resolution in pets is less than people. For
example a dog would need to stand 20 feet from the same
object to see the object as well as a person standing 75
feet away. It turns out about 66 percent of Rottweilers
are near sighted, and many Australian Shepherds are far
sighted. In cats their visual acuity is slightly worse than that
of a dog. For cats what they gain in terrific night vision is
lost in daytime acuity.
Moving beyond color, visual fields are determined by eye
position. The more forward the eyes the more binocular
vision and depth perception. Dogs and cats have binocular
vision looking forward. They have monocular vision
laterally, and a blind spot to the rear. In cats the blind area
is larger than in dogs, at 160 degrees (of 360 degrees) of
the visual field; and their binocular visual field is larger than
the dog at 140 degrees compared to 60 degrees.
Clearly dogs and cats see the world differently than
we do, yet there is enough overlap that we can visually
understand each other.
In contrast, herbivores with their lateral eye orbits have a
small forward binocular field but have no blind spot to the
rear. This means they have 360 degree panoramic vision.
Emails and Letters from Adopters
Dear WSHS,
Linus (Captain Hook) is awesome and he has adapted to my home and his two older
brothers from WSHS. He became large and in charge on day one. I usually take a week to
introduce a new cat, however he didn’t like being in a bedroom by himself. His brothers still
let him barge right in and take their food! My home has become one big playground for
them, as there is non-stop playing, chasing, etc. He wakes me up five times a night, kissing
my face, kneading my hair and snuggling. He is loved to say the least, and I can’t believe
how big he is getting! I’ll gladly give you a write-up on Yelp or your site, as he is the fifth cat
I have successfully adopted from your facility. He now has three levels of a home to roam
and play in, and he can snuggle up to his brothers and get a lot of love. Thanks again!
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