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.
Thunder is the silver sable and Bama is the white. They are shiloh shepherds. Thunder’s color is of the old GSD colors.
for home
And a well armed kitty at that too! :-)
Too funny.
I love Schnauzers. My dad had two. I have never seen a standard. I bet she is pretty.
Taken when she was 2 or 3 years old.
Stealing a kiss from a neighbor's kid.
Oh, what a cutie pie. And so lovable.
Mercy me! Those are some beautiful mastiffs!
Awesome, just so lovely.
Yes, the males are so much larger than the females...the females really LOOK like females, dainty for a mastiff, LOL!
Thunder and Bama—Just lovely, what a great photo, with them together. They have such soft eyes...
Nice dogs! How can I post my dogs picture on my home page??
Yes, they do.
You know what’s interesting. Everyone always comments on their eyes. It looks like they are looking right into your soul.
Just a note of history. Bama(white), Thunder’s dad and Fuji(white sable) my girls’ mom are the only two white on white Shiloh Shepherds that have ever produced a litter of all whites or white sables as they are called. You will see white sables; but they have been produced by multicolor Shilohs. And I happen to own two of them. Got really lucky; not just because of that; but they are the sweetest girls and I love them so much.
I haven’t posted on the home page; but let me see if I can find the Freeper or anyone else if they know, that helped me.
You do need something, I believe, like photobucket.
I’d say he could be part scottsh deer hound or possible a little bit greyhound...based on the pic I just saw.
I’ve never seen a pharoah hound before! Looks just like the dogs in the Egyptian exhibits I’ve seen.
I love your beautiful dog photos, and I watch the shows religiously, they are so entertaining; but I am just an ordinary dog lover, we’ve had so many rescues over the years, always got adults and sometimes they were older than advertised, but all were wonderful
Never did have a bad dog, one of the best was a beautiful mix of 1/2 Great Dane that I got as a puppy; he was a yard dog, and just wonderful. Interestingly, he never got a flea or tick despite living outdoors all summer (In winter he came in at night.) I guess he nibbled on something or rolled in something that kept him free of them. I’ve never heard of that before or since.
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