What dogs see

 Freckle does email and Ceilidh snoozes  This morning I settled in on the couch (I should say the  dogs’ couch) with my laptop to read email. Freckle stepped up on the footstool and slithered in beside me, resting her chin on my arm since I wouldn’t let her put it on the keyboard. As I moved the cursor around on the computer screen and began opening browser windows, Freckle followed with her eyes. When a new window opened, her eyes grew big and she watched with obvious interest. She tilted her head and tried to sniff the screen. Ceilidh has never been interested in the computer monitor, but she will bark at animals (even cartoon animals) on the TV, causing us to wonder how blind she really is. Anyway, this morning I began to wonder just what Freckle was seeing.

I Googled “what dogs see” and found the “Catalyst” website. It’s an Australian science TV program and in 2003 they did a program called “Dogs’ Eyes.” Apparently veterinary scientist Paul McGreevey had been wondering the same thing … what DO dogs see? He said that he found it odd that the textbooks said that dogs all had the same eye structure and that they all saw the world the same way given the diversity of dog sizes and shapes. McGreevey researched different breeds, checking the size and shape of their skulls and noses. He began collecting eyeballs from dogs who had passed away so that he could measure them (shades of Michaelangelo’s research here!). He found that yes indeed, eyeball shapes vary depending on the breed.

McGreevey’s collaborator in Perth, a neurosurgeon named Alison Harman, was examining the retina behind the eye and found that different dogs had different retinas. Some dogs have the type of retina with a “visual streak” meaning that they have great vision, including terrific peripheral vision. But some dogs have a retina with “a dense, area centralis” instead. The “vision cells” are arranged in one spot rather than in a “streak.” This means that like humans, dogs with the “area centralis” see clearly what is in the middle of the field of vision but … the edges not so much.

Now … here’s where the story gets really interesting! McGreevey and Harman say that their research indicated that a dog with a short nose had an area centralis with three times the density of cells found in a visual streak. According to the TV narrator, “It means that short nosed dogs with their area centralis see in much higher definition than other dogs.”

Referring to short nosed dogs, McGreevey says, “So when they’re looking at the owner’s face and different nuances of the owner’s expressions, maybe they’re getting a bit more information than a long nose dog. This is perhaps a way of explaining how attentive and charming short nosed dogs are.” [emphasis mine]Freckle LOVES the Internet–where nobody knows you’re a dog

I knew it! Before you know it our girls are going to be asking for their own laptops and High Definition TV. Anybody know of a support group for short nosed dogs living with high definition vision?

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One response to “What dogs see

  1. We could have told you how good we see if you had asked!

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