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Why Do Dogs Eyes Glow?

Why Do Dogs Eyes Glow?

Why Do Dogs Eyes Glow?

Have you ever noticed that the whites of a dog’s eyes seem to glow? This is because there is a layer of cells called the tapetum lucidum which reflects light and makes their eyes shine. It is also what makes it possible for them to see better in the dark.

It's not just dogs with this characteristic though, many animals such as cats, cows, horses, and deer have this reflective layer in their eyes. Humans do not have this layer which is why our eyes don't produce that reflection.


There are some benefits to having this reflective layer though such as helping them identify any potential predators or prey without having to rely on sight alone.


Here are some interesting facts about dog's eye and how it reflects light.


Why do dogs' eyes glow in the dark?

 

These animals have a thin layer of light-sensitive cells called the tapetum lucidum which shines in low light conditions.


This is also what makes the eyes of many animals glow in the dark. Humans do not have this layer which is why we can see better in the dark.

 

Can a dog see better in the dark than a human?

 

If your dog has good vision in low light conditions then yes. Dogs’ eyes have more rods and cones than human eyes.


Humans have two types of cone cells. Rods are light sensitive and can only see red, green, or blue. The cones are responsible for color vision.

 

How do dogs see in the dark?

 

They use different light sensitive cells called cones to see in the dark. There are three types of cones. Cystophanes and Ursinic to be exact.

 

What are the tapetum lucidum?

 

The tapetum lucidum is a layer of tissue in the eye that is mostly made up of light sensitive cells. These are called rods and cones.


hese cells absorb and convert light energy into an electrical signal that travels to the brain.


It is thought that these rods and cones are what enable you to see in the dark.

 

The cells that make up the tapetum lucidum are shaped like a fan and therefore reflect a lot of light to the back of the eye so that the brain can detect it.


This helps them to avoid threats such as other animals or dangers such as a predator.

 

When the animals in question are day-time animals then this reflective layer is kept hidden within the surface of the eyeball.

 

How Does This Reflect Light?

 

It is thought that the entire tapetum lucidum is made up of rods and cones.

 

Why do dogs have this characteristic?

 

It’s all down to our evolution. It seems to be a side effect of how our eyes evolved.


A long time ago when the first dogs were domesticated they roamed in packs which made the big predators a little more hesitant.


This was a great advantage for humans as it meant that the dog’s could keep an eye out for any potential predators before it was too late.

 

The reflective layer in dogs eyes seems to be linked to the development of the tapetum lucidum in our eyes. Since dogs use their eyes to search for food it makes sense that this layer is necessary for them to be able to see further into the darkness.


Although we no longer live in the caves and are far more advanced than dogs they do have these reflective layers in their eyes which helps them better see in the dark.

 

What are the benefits of having this reflective layer in their eyes?

 

Darkness

 

It is actually the dark that helps keep your eyes healthy, because it stops the surface cells from oxidizing and discoloring.


This means the pigment, the trabecular cells that help in our vision, is more effective and produces better contrast and sharpness.

 

There are certain breeds of dogs that require a lot of night time exposure to maintain their eye health. This is because in breeds that have to work at night, such as hunting dogs, these dogs have to be able to see very clearly without a lot of cloud cover or light pollution.

 

In addition, eye white is much whiter in dark conditions, so if your dog does suffer from eye condition such as over producing its natural eye lubricant then you may need to use additional eye lubricants in order to help maintain their eyesight.

 

Conclusion

 

Dogs have eyes that glow red or green depending on their mood, health, and how happy or excited they are. This feature is known as iris colouration, it’s often referred to as "dog's eyes" or "golden eyes." 

 

It’s amazing that we are able to understand our canine friends like this, and I hope this article shed some light on the subject.

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