Houndsight is 20-20

Posted by on Jan 15, 2010 in Health & Wellness, Paws for Thought | 0 comments

My eyesight is horrible…I mean bad… really, really bad.  At my last eye exam the doctor displayed the largest E on the brightly lit screen and I couldn’t decipher what it was. Sadly, I couldn’t read anything on the screen at all. Thank God for corrective lenses!

Have you ever thought about what your dog sees and doesn’t see? Is Fido’s vision 20/20? In one simple word, no. His vision is more like 20/75! What a person can see from 75 ft away a dog can only see at 20 ft.

You probably have heard that dogs are color blind. That their world view is in black and white. The latest research has shown that this is not the case. Because the retina in a dog’s eye contains about 1/10 the amount of cones (cones provide color perception and detailed sight) as a human’s eye their vision is more like someone who is color blind. Distinguishing red, green, orange and yellow is impossible for dogs. Studies have shown that they can pick out blue/violet and yellow, however. They can also differentiate between shades of gray.

Don’t feel too bad for them though. Dog’s can see much better in dim light than their two legged parents. They are also excellent at seeing things in M O T I O N. For all of you who have dogs that can run down a Frisbee and pluck it out of mid air or whose dog can catch a ball at any angle and height…or have witnessed your pooch chase down a lizard across the yard at dusk…you know what I mean.  Why is this possible? A dog’s retina may be lacking in the cone department but it is rod dominant. Rods provide the ability to detect motion and to see things in dim light.  AHA! This explanation makes perfect sense when you think of dog’s evolution. Our pet’s wild ancestors were hunters and predators chasing prey at dusk or at night.

Night vision and detection of movement was crucial for survival of the species.  Let’s apply this knowledge to our modern dog’s life. Think about training your dog. If you have taken a training class in the past you most likely were taught hand signals as well as voice commands. Your movement reinforces your voice and satisfies your dog’s sense of sight.  Even more innate is a dog’s ability to distinguish even the slightest movement in other dogs. This is how they understand the hierarchy of the pack, the messages being relayed and how they should respond. In fact, this is how they learn about us…their humans. They are very tuned in to our body language and take their cues from our actions. Don’t expect your dog to know who you are from a distance but as soon as you make one of your characteristic moves they will realize who you are. 

A dog’s sight or lack of vision in bright light…is supplemented by their other, stronger senses of smell and sound. Going back to our ball example, a dog can follow the ball as it fl ies through the air, but as soon as it hits the ground and stops rolling, their sense of smell kicks in and they “sniff out” their round prize. Or, our other example of knowing you from a distance…as soon as you use your voice they will identify you and of course they intimately know your scent. 

So, even though Fido’s sight may not be 20/20 it is perfectly made to suit his needs and has worked for his species for millions of years!

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