Posted on 11/08/2007 7:09:03 PM PST by 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.
your dogs look wonderful but you are lacking a beagle!
wife-o-buckhead
She is a real beauty.
Here’s my godson puppy, Angus, his brother, Rumor(2 mastiffs)and their brother Logan and Otter(the labs). The mastiffs think they are labs. LOL
http://www.youtube.com/watch?v=1QQzbCmlZM4
Isn’t this fun sharing pics. I just love it.
all 4 of yunz are cute!
As long as we're sharing pics, I still think this is the greatest photo of the greatest dog ever taken...
"Genetic (mitochondrial DNA) testing being performed at the University of South Carolina, College of Science and Mathematics, indicates that these dogs, related to the earliest domesticated dogs, are the remnant descendants of the feral pariah canids who came across the Bering land mass 8,000 to 11,000 years ago as hunting companions to the ancestors of the Native Americans."
What a great looking dog. He is magnificent.
Funny that I replied to your posting since I have a cat named, Spunky!
I’ve got a dog with cataracts as well. She’s also lost most of her hearing. Is that what we can expect when we get older?
Easily. She's a b!t¢h.
Afraid so. My last visit to the eye doctor he said I had the beginning of cataracks. I think I must be losing my hearing also as I can't hear a word my husband says. But maybe that is because he has the TV blaring and then tries to talk to me in a normal voice. :-)
Oh, what a pretty, pretty girl. She is a little cutie.
Do you mean to tell me that Hillary wasn’t the first thing to cross your mind when you read the phrase “glowing eyes”?
Wow, that’s awesome. I’m guessing she is an indoor cat, or you don’t live in a coyote area!
Yep. She is indoor; and yes we do have coyotes.
I love your little baby. She has that sweet face we all love.
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