Monday, June 25, 2012

Monday Medical Issues: why do pets' eyes glow?

Okay, this isn't technically a medical "issue" - but hey, it's a cool topic!

If you’ve taken many pictures of your dog, cat or ferret, then you’ve seen it: laser eyes!

It’s a phenomenon specific to only a handful of animals; other species like rabbits, guinea pigs – even humans – just don’t genetically have that "special glow."

Those that do are gifted with a unique surface in the eye behind the retina called the tapetum lucidum. This special surface is composed of 15 layers of glittery cells that combine to create a single reflective layer to capture and enhance light.

Any light that gets past the retina is bounced back at it, giving the photoreceptors in the retina more data - and a second chance - to resolve the image.

Basically it functions a bit like nature’s very own night vision goggles! Cool, huh?

Why do Siamese eyes
glow red instead of green?

I had never really paid any attention to the color of the boys' eyes when they glowed until someone mentioned this to me. The claim was that Siamese eyes glowed red while all other breeds glowed green.

Of course, I had to test this empirically. So out came the camera.

Test Subject One: Allie

Yep, green!

Test Subject Two: Faraday

Look! Red eyes!

Test Subject Three: Maxwell

Seriously red eyes! We were shocked at how red, in fact.
(This photo undoctored)

Of course, that begs the question, what causes this?

Contrary to what Wikipedia states (you do know Wikipedia can be wrong, don't you?) Siamese cats do have that cool night vision layer behind their retinas. But unlike other breeds, there is a hereditary abnormality in Siamese that weakens the tapetum lucidum. So a Siamese cat probably won't see as well in the dark as other kitties.

Since Faraday is a Tonkinese (a blend of Siamese and Burmese), you'll notice his eyes are less red than Maxwell's. He probably sees better at night that Maxie.

So there you have it.
Cats: cool, built-in night vision goggles.
What's not to love?

article sources:

"Hereditary abnormality in tapetum lucidum of the Siamese cats. A histochemical and quantitative study,"  Histochemistry, 1982;75(1):1-9. Published by National Institute of Health's PubMed site 

"Why do animals' eyes glow in the dark?" - NPR

"How Stuff Works" 


  1. Oh I'm frightened! Scary eyes that send out rays!
    Best wishes Molly

  2. Cats are just amazing creatures :-)

  3. Mommy thinks all of us shoot out green lasers but she'll check to be sure. Thanks for sharing!

    1. Ooh! Let us know who shoots what color lazer!!

  4. Interesting! We are a green laser family, but we don't feel common at all!! lol

    1. Maxwell: Oh, you shouldn't! Green lasers are night vision goggles at full capacity! Us meezers have, uh..."reduced intensity" night vision.

      Allie: Face it, Max, green is the BEST!

  5. you know Deb Barnes of the blog Zee & Zoey? HER eyes glow like a cat! She says she IS part I completely believe her!

  6. MOL to Caren!! See, I told you I wasn't kidding.... I've always known I was part cat!!! (For reference Lisa, Angie of Catladyland, posted a picture of me with Peter Wolf at BlogPaws.... my eyes were definately glowing!)

    On another note Lisa, really missed seeing you and hope you had a great time working with Illuminate!

    1. Missed you guys SO much! And I'm holding the date on my calendar for next May!! heading over to hunt down Angie's photo now!!

  7. Now we have to check EK's eyes. He's a Siamese mix, but I think his eyes glow green. I'll report back after we check his lasers!

    1. Laser banks standing by! We'll wait to hear which side EK lands on!

  8. oh my cat! Now Mom will be bugging efurry new Siamese cat they get at the Kitty Corner Shelter where she and Dad volunteer...poor cats...sorry guys!

    1. MOL!!! You'll have to report back their findings!

  9. Very interesting! My heart cat Tutu was Siamese and her eyes were always red in pictures. She was a beautiful girl, but not terribly photogenic because of her red eyes in pictures.

    Your pal< Pip

  10. Mica Minnie Moo's eyes glow red, of course she is part Siamese. White cats with blue eyes are usually deaf, but if their blue eyes are because one of their parents are a Siamese, then they aren't deaf. The mom had a white blued eyed cat who wasn't deaf and his eyes glowed red too. Its a little freaky seeing glowing red eyes at night.

  11. Whoa! That's the most inneresting fact! LOVE that red glow! Sometimes my eyes glow pink. I wonder if there is siamese somewhere in my ancestry.

  12. That's cool! Cosmo's eye are particularly glowy, kind of an other worldly blueish color!
    Your pals,
    Diane and Cosmo

  13. Me always tells peoples my eyes glows red because me is the Cat From Hell!
    Now everyone will know its because me is a Siamese!

  14. Ooohhh... I'm gonna have to check CJ's eyes. He's part Siamese! Interesting post!!!

  15. Wow, we just realized that only Iza an I have red eyes. TBT NEVER has ta use the red-eye feature on Photoshop fer Marley... ~ Ayla


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