How Well Do Dogs See At Night?

Science Daily ^ | 11-8-2007 | University of Wisconsin - Madison.

[blam]

How Well Do Dogs See At Night?

ScienceDaily (Nov. 9, 2007) — A lot better than we do, says Paul Miller, clinical professor of comparative ophthalmology at University of Wisconsin-Madison.

Dogs have good night vision, due in large part to the tapetum, a mirror-like structure which reflects light, giving the retina a second chance to register light that has entered the eye. This is also what makes dogs eyes glow at night. The dog is holding a toy in her mouth. (Credit: Michele Hogan)

“Dogs have evolved to see well in both bright and dim light, whereas humans do best in bright light. No one is quite sure how much better a dog sees in dim light, but I would suspect that dogs are not quite as good as cats,” which can see in light that’s six times dimmer than our lower limit. Dogs, he says, “can probably see in light five times dimmer than a human can see in.”

Dogs have many adaptations for low-light vision, Miller says. A larger pupil lets in more light. The center of the retina has more of the light-sensitive cells (rods), which work better in dim light than the color-detecting cones. The light-sensitive compounds in the retina respond to lower light levels. And the lens is located closer to the retina, making the image on the retina brighter.

But the canine’s biggest advantage is called the tapetum. This mirror-like structure in the back of the eye reflects light, giving the retina a second chance to register light that has entered the eye. “Although the tapetum improves vision in dim light, it also scatters some light, degrading the dog’s vision from the 20:20 that you and I normally see to about 20:80,” Miller says.

The tapetum also causes dog eyes to glow at night.

Adapted from materials provided by University of Wisconsin - Madison.

[freekitty]

Your family is beautiful. Thanks for sharing.

[Mjaye]

Thanks, that was some extra fine music...

[Joe 6-pack]

"Your family is beautiful..."

I came from a highly dysfunctional family, but they all got better after I left home ;-)

[freekitty]

Me too. LOL

[freekitty]

You are welcome.

[freekitty]

This guy likes Elvis. LOL

[blam]

You Ain't Nothing But A Hound Dog

[freekitty]

I love it.

Does everyone know that Jerry Lee Lewis cousins are Jimmy Swaggart and Mickey Gilley?

[shibumi]

I think it’s time for someone to post “Master of the Obvious.”

[Brad’s Gramma]

LOL!!!

That looks AND ACTS like some dawg I know & love.....

:)

[Brad’s Gramma]

He was a Hurricane Katrina abandonee that I rescued

Ya done good....thanks for that act of kindness!

[blam]

"Does everyone know that Jerry Lee Lewis cousins are Jimmy Swaggart and Mickey Gilley?"

I think I've heard that before.

[AlaskaErik]

My chocolate lab at five and a half months old doing one of her two assigned chores. The other one is raising the alarm when strangers come to the door. This is a zoom shot. It's about 150 feet from the front porch to the end of the driveway. In the winter it's really nice to get the paper without getting dressed up and freezing my butt off!

[IrishCatholic]

Is that a mastiff lower left? Looks exactly like mine when he was a year old.

[aliquando]

Amen Brother.

[Joe 6-pack]

Yep that’s an 11-month-old mastiff. Well spotted!

[TASMANIANRED]

They can do cataract surgery on dogs...

[TASMANIANRED]

My Black Labs glow green..

[BunnySlippers]

Wow! Fabuous! Keep them coming ...

Rockin out here at home.

[SunkenCiv]

:’) I’m always nice to old timers, so I won’t nitpick a couple of the details of that. :’)