[ SHOWGSD-L ] Ask Dr. Richards - Dog vision
- From: Susan Madlung <stormygsd@xxxxxxx>
- To: Vontan@xxxxxxx, showgsd-l@xxxxxxxxxxxxx
- Date: Sat, 07 Oct 2006 12:33:35 -0700
/from http://www.vetinfo4dogs.com/dogsee.html
Dogs have binocular vision over about 80 degrees of their visual field,
which is enough for good quality binocular vision. This does vary some by
breed, with collies probably having a smaller area of binocular vision than
a golden retriever due to the placement of the eyes and length of the nose.
Dogs have dichromatic vision, meaning they see in only two colors, which
might be confusing
I have a friend who is blind in one eye who can still catch Frisbees pretty
well, so I'm not sure that binocular vision is essential for tasks like this
but dogs do have binocular vision normally and should have good depth
perception.
Mike Richards, DVM
1/24/2003
How dogs see
Dogs can see in much dimmer light than humans. This is because the central
portion of a dog's retina is composed primarily of rod cells that "see" in
shades of gray while human central retinas have primarily cone cells that
perceive color. The rods need much less light to function than cones do.
Dogs can detect motion better than humans can.
Dogs can see flickering light better than humans. The only significance to
this appears to be that dogs may see television as a series of moving frames
rather than as a continuous scene.
Dogs do not have the ability to focus as well on the shape of objects (their
visual acuity is lower). An object a human can see clearly may appear to be
blurred to a dog looking at it from the same distance. A rough estimate is
that dogs have about 20/75 vision. This means that they can see at 20 feet
what a normal human could see clearly at 75 feet.
Dogs are said to have dichromatic vision -- they can see only part of the
range of colors in the visual spectrum of light wavelengths. Humans have
trichomatic vision, meaning that they can see the whole spectrum. Dogs
probably lack the ability to see the range of colors from green to red. This
means that they see in shades of yellow and blue primarily, if the theory is
correct. Since it is impossible to ask them, it is not possible to say that
they see these colors in the same hues that a human would. Whether or not
the ability to see some color is important to dogs or not is hard to say.
Also consider the perspective that dogs see the world from. A dog with its
eyes about 12 inches off the ground certainly sees the world a different way
than a human with eyes about 48 inches off the ground like many 5th graders.
As humans we tend to think of dog's visual capabilities as inferior to ours.
It is different but it may suit their needs better than possessing accurate
color vision would.
Michael Richards, DVM
How dogs see color
Q: Dr. Mike, I'm a fifth grader from Grass Range, MT. This year I'm doing my
science fair project on dogs. Seeing if they're colorblind or not. My
teacher said to find out as much info as possible. So I was wondering what
you could tell me about their sight. Do you have any proof about if they're
colorblind or not.
A:. The current thinking is that dogs see in color but not in the way that
humans do. I will try to find some information on this for you (I know that
there was an article in one of the veterinary journals, but I can't remember
which one) and forward it on.
The latest article on this discussion that I can find a reference to is the
December 1995 issue of the Journal of Veterinary Medicine. I haven't been
able to find this journal in my collection, though. Maybe your vet would
have it. I'll keep looking.
If memory serves me right, the thinking is that dogs only see blue and
yellow or red and yellow (couldn't remember for sure) because they have many
less of the cones (color vision cells) than people. On the other hand, they
have many more rods (low light and motion detecting cells) so they see much
better in the dark and they can detect much smaller motions than humans.
Michael Richards, DVM
Sue Madlung - Shadowacre Reg'd German Shepherds
http://www.shadowacre.com
----- Original Message -----
From: <Vontan@xxxxxxx>
To: <showgsd-l@xxxxxxxxxxxxx>
Sent: Saturday, October 07, 2006 12:15 PM
Subject: [ SHOWGSD-L ] Re: DOGS DO SEE COLORS
>
> In a message dated 10/7/2006 12:42:19 P.M. Eastern Standard Time,
> wynsum@xxxxxxx writes:
> << If I can find the article, written about 8 yers ago in Dog World, dogs
> see blues and greens >>
>
>
>
> Yes I remember that article too, they see colors but not the whole
spectrum.
> Not shades of gray as was originally thought.
>
> Yvonne
> creekvue.com
>
>
>
============================================================================
> POST is Copyrighted 2006. All material remains the property of the
original author and of GSD Communication, Inc. NO REPRODUCTIONS or FORWARDS
of any kind are permitted without prior permission of the original author
AND of the Showgsd-l Management. ALL RIGHTS RESERVED.
>
> ALL PERSONS ARE ON NOTICE THAT THE FORWARDING, REPRODUCTION OR USE IN ANY
MANNER OF ANY MATERIAL WHICH APPEARS ON SHOWGSD-L WITHOUT THE EXPRESS
PERMISSION OF ALL PARTIES TO THE POST AND THE LIST MANAGEMENT IS EXPRESSLY
FORBIDDEN, AND IS A VIOLATION OF LAW. VIOLATORS OF THIS PROHIBITION WILL BE
PROSECUTED.
>
> For assistance, please contact the List Management at admin@xxxxxxxxxxxx
>
> VISIT OUR WEBSITE - URL temporarily deleted due to AOL issues
>
============================================================================
>
>
> --
> Internal Virus Database is out-of-date.
> Checked by AVG Free Edition.
> Version: 7.1.394 / Virus Database: 268.12.9/458 - Release Date: 9/27/2006
>
>
============================================================================
POST is Copyrighted 2006. All material remains the property of the original
author and of GSD Communication, Inc. NO REPRODUCTIONS or FORWARDS of any kind
are permitted without prior permission of the original author AND of the
Showgsd-l Management. ALL RIGHTS RESERVED.
ALL PERSONS ARE ON NOTICE THAT THE FORWARDING, REPRODUCTION OR USE IN ANY
MANNER OF ANY MATERIAL WHICH APPEARS ON SHOWGSD-L WITHOUT THE EXPRESS
PERMISSION OF ALL PARTIES TO THE POST AND THE LIST MANAGEMENT IS EXPRESSLY
FORBIDDEN, AND IS A VIOLATION OF LAW. VIOLATORS OF THIS PROHIBITION WILL BE
PROSECUTED.
For assistance, please contact the List Management at admin@xxxxxxxxxxxx
VISIT OUR WEBSITE - URL temporarily deleted due to AOL issues
============================================================================
Other related posts:
- » [ SHOWGSD-L ] Ask Dr. Richards - Dog vision
