Pupil Dilation In Dogs
If you’ve ever taken a picture of your dog or stared at him at night, you’ve probably noticed that his eyes glow in the dark, perhaps due to the light emitted by the camera’s flash. This happens because of the dilation of the dogs’ pupils. Want to know more about it?
Dogs’ eyes are usually beautiful and intense during the day, but at night they seem to change. They glow green, or sometimes yellow or purple, drawing our attention. But what makes this phenomenon happen?
Let’s meet the canine eye
Before knowing why certain phenomena occur in our dogs’ eyes, we must try to understand how it is constituted.
The retina, which is the back of the eyeball, is formed – in parts – by cones and rods, two cells with high sensitivity to light. Cones perceive color and the image clear, while rods do the same with movement and are very sensitive to low light.
Dogs have retinas with more cones than rods, which helps them to see better than us in the dark. However, they have fewer cones than us, which prevents them from seeing colors with the same range and intensity as people.
Light enters through the pupil, which dilates. From there, it passes to the lens, a lens that, the bigger it is, the more light it will be able to absorb.
Why Dog Pupils Dilated
By looking at the makeup of dogs’ eyes, we can understand why pupils dilate and why our pets’ eyes glow in the dark.
According to recognized ophthalmologists who are dedicated to the study of animal vision, canine eyes react to light differently than we do. That’s because they have a light-reflecting surface known as a “tapetum lucidum”, which lies between the optic nerve and the retina.
The “tapetum lucidum” acts as a mirror that reflects light and sends it to the rods and cones so they can absorb it when there is little light, such as at night.
Dr. Miller of the Memphis Animal Ophthalmology Clinic explains verbatim:
Why is the glow in dogs’ eyes a different color?
When we see the dilated pupils of dogs, they can be different colors. This is due to the amount of zinc or riboflavin the animal has. Depending on how much it contains, the glow color of these animals’ eyes can show up in one form or another.
Another aspect that can influence is the animal’s fur color. For example, dogs with white fur and light eyes usually have a reddish tinge to their eyes, while those with dark fur usually have a blue to purple hue.
Age is another influential factor, as some parts of the eye thicken and receive less outside light. This can change the color of the dog’s eye glow.
All dogs, according to experts, are born with a “tapetum lucidum” that varies from blue to purple, although, after 16 weeks of life, this can change. That’s why, in some dogs, they appear yellow or green. There is no clear rule in this regard.
Have you ever wondered about the cause of dilated pupils in dogs and why they glow in the dark? Well now you have the answer!
