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.
Her brothers went to live on a farm, and eat live animals (I personally saw them eating minnow-type fish as they flopped around on the grass), and do not like to be picked up.
From day one I made a point to handle her often, and would carry her around on my arm to get her accustomed to us. She likes to be handled, and will tolerate our love, but she's not very loving herself! There is a 3-minute window of opportunity when we come home from work when she meows and follows us around; I use that time to hug and squeeze her. She still will not let us rub her belly though.
You will love it.
Hillary is very rarely the first thing to cross my mind. I tend not to concentrate on evil negatives. ;-)
Ah, you have a feral cat. They are something. Cats have their own personalities. Have a little black on, Murphy, who is a tiger. Was born outside to ferals; but loves to be loved with kisses and hugs; but will fight with the best of them. LOL
I love the poster. Had one siamese. She didn’t care for people; but loved to fight with hubby. He loved her and I did too. She was great. Only wanted to be with us. Hated the dogs. Even got on top of one their cages and started swating at the poor thing. She really did love us; though.
My daughter’s taking an online exam for a college course right now, and I promised her I wouldn’t do any big downloads until she’s finished it. It’s for Spanish and it has audio clips and such.
Click on my screen name to see my mastiff at 18 months. He’s almost 4 now.
Nice dogs. Is that a mastiff in the bottom left? Your niece is pretty. :)
He is adorable. Who is the little one?
When you get the chance. I love to see people’s families.
Poor baby.
She is my little minpin, she’s 11 now, iirc. I keep forgetting if she’s 10 or 11.
That was hot.
I once saw Fats performing in a dinner club. Fabulous show.
She is precious.
Great, wasn’t it. I have posted a link to a couple of boogie woogie dancers who are really fabulous somewhere on this thread. If you get a chance; take a look.
I love to see photos of mastiffs...I got mine for my husband, for his birthday 3-1/2 years ago. He said it was the best birthday he’d ever had...
I love the photos you put up. Are they your mastiffs? Are they by any chance the American Mastiffs from Flying W? Mine is.
No they are not mine. They along with the labs belong to some good friends of mine. You are not going to believe this; but I have heard of the Flying W. LOL
Angus and Rumor are both from Thousand Oaks Mastiffs. Angus is the nephew of Sherman, who until recently retired was the top mastiff in the country. Rumour is Sherman’s son. Watch Angus. He will be at Westminister for sure. I will find a pic of Angus and his sister, Barbie(owned by breeder’s daughter) It amazes me the size difference between the males and females. I think Angus is already at 225 lbs. He is 2 weeks younger than my shilohs and I have 114 lb and 100 lb females. LOL
I love the mastiffs.
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