Through a Dog's Eyes
5 minute read
A dog's eyes are far more diverse than our own. The different shapes from almond to round and oval to triangular reflect the different jobs that dogs do and the different emotions they generate in their owners.
I love a dark oval eye, for me it is the epitome of kindest.
Dogs see the world differently to us. Our eyes are set facing straight forward, giving us great depth perception and binocular vision which is needed for judging distance and seeing things in 3 dimension. A dog's eyes are set wider and at an angle to their head, therefore they have less depth perception but a wider field of vision, allowing them to see predators coming from behind more easily. Also the size of their noses would be a greater obstruction to their vision if they had front facing eyes. Dogs also have better night vision for hunting in the dark and enhanced motion sensitivity so they see moving objects much easier than stationary objects, a critical characteristic of canine vision.
With these attributes, something has to be compromised and it is that they see with a limited range of colours. Dogs see like colour blind humans.
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How do eyes work?
Light enters through the front of the eye, passes through the cornea and the lens and is focused on the retina. The retina contains colour sensitive cones and motion and light sensitive rods.
Humans have 3 types of cones making their colour range greater than a dogs, who have only two cone types. This leaves dogs unable to distinguish between red and green meaning a red ball thrown onto green grass is a challenge for a dog to see. However, dogs in contrast to humans have a larger lens and light capturing surface containing more rods, which gives them well developed night vision and motion detection. This greater light reflective surface is evident when we shine a torch at our dogs and capture the spooky glow.
What a dog sees (on the right)
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Choosing dog toys
When choosing dog toys remember although easily visible to us, red is the most difficult colour for a dog to see and if stationery can be hard for your dog to find on green grass, where as a blue ball will stand out easily.
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One last thought; with wide angled vision but poor depth perception and a large obstructing nose, a ball thrown straight at a dog's nose may be missed where as one thrown from the side is more easily caught.
Julie Harris
