Why do most dogs have brown eyes?

Who doesn’t love it when our dogs look at us with those puppy dog eyes? Whenever our canine buddy gives us a heart-melting gaze, we can’t help but give in. To long-time pet owners, our dogs’ eyes are a channel of affection or communication. They stare or even glare if they want to tell us something. 

Speaking of dogs’ eyes, they pretty much function like people’s eyes. Even the anatomy of a dog’s eyes is practically the same as those of humans’.  Different dogs may have different eye colors too. However, there’s one color that stands out – brown! 

So why do most dogs have brown eyes? Quick answer, genetics. Two main pigments dictate the color of dogs: black (eumelanin) and red (phaeomelanin). By default, eumelanin is produced in dogs’ noses and eyes. Merle gene “dilutes” it to produce the default dog eye color, brown.

If your dog doesn’t have the default chocolate brown eyes, then your dog’s genes are at play here. But that’s not to say that your dog is not normal! 

That’s just how genes work. They act like a “manager” that tells some cells to create eumelanin, other cells to create phaeomelanin, and in some cases, tells them not to create pigments at all. 

So now we know that several genes control melanin pigments and where they are produced in dogs. For instance, in your dog’s coat, nose, and eyes. While dogs produce only two basic melanin pigments, genetics manipulates them to produce other ranges of canine eye colors!

In summary, below are scenarios that can determine our dog’s eye color:

  • Default eye color – Eumelanin pigment is produced in your dog’s eyes and diluted as normal by the gene called merle. Your dog will have pure brown eyes.
  • Recessive genes (B or D) modify or dilute eumelanin pigment in dog’s eyes – Again, certain genes affect dogs’ eye color. Depending on the breed, this type of gene modification or dilution occurs in varying intensity levels. Thus, resulting in varying eye colors or shades, such as amber, green, yellow-green, and grey.
  • Other genetic modification or absence of pigment – When the merle gene abnormally or excessively dilutes the black eye pigment, OR when there is a loss of pigment (albino dogs), your dog ends up having crystal blue eyes.    

(Note: In puppies, melanin production doesn’t go full-on straightaway. That’s why puppies may sometimes have blue eyes but eventually develops into a different shade once they mature, once melanin production increases)

Dogs Eye Colors Chart

Dog Eye ColorWhy
Brown Normal production of eumelanin in the dog’s eyes, diluted by merle
Amber, green, yellow-green, greyEumelanin is modified or diluted by the recessive genes (B or D) in certain dog breeds
BlueExcessive dilution by merle gene or loss of pigment in dog’s eyes like in dog albinism
Why do most dogs have brown eyes?

Some Interesting Facts About Dogs’ Eyes and Vision

  1. Dogs are not color-blind. Dogs seeing in only black and white is a myth. They can perceive colors too! To our four-legged friends, wavelengths of blue and yellow or combinations of these shades are visible. So if we look through the eyes of our canine pets, the things around us would be blue, grey, and yellow. 
  1. Dogs’ visual field is about 250 degrees. Since their eyes are placed on the sides of their head, they cover a wider peripheral vision compared to humans.
  1. Their eyes glow in the dark.  If you meet a dog in a dark alley, chances are their eyes glow like magical creatures. Thanks to a tissue called tapetum lucidum, a lining behind the retina that reflects light like a mirror. 
  1. Dogs can also see well in darkness. Unlike people, dogs can see even in the dark. Why? Like other mammals, canines have larger pupils and light-sensitive rods that help them see in poor lighting conditions.
  1. They have a third eyelid. Dogs (like most animals)  have a third eyelid or a nictitating membrane that serves as an eye shield or protection. 

What are some top dog eye problems?

Certain eye problems that we commonly see in dogs are due to bacterial infection, inflammation, lack of grooming, accidents, or self-injury. 

  • Corneal ulcers – corneal damage or injury caused by trauma
  • Pink eyes or conjunctivitis – an eye infection on the outermost layer of the eyes
  • Dry eyes – lack or loss of tear production, which can be very painful for our canine pets
  • Eyelid cyst – also known as gland tumors that are usually benign
  • Cataracts – when the eye lens become clouded, causing blurriness or even blindness
  • Glaucoma – when there is an increase in eye pressure causing pain and even blindness
  • Cherry eye – this occurs when your dog’s third eyelid becomes swollen

With proper preventative care and treatment, pet owners can ensure that their furry pets always have a healthy and beautiful pair of eyes. 

Related Questions

Why do most dogs have brown eyes?

What is the rarest eye color for dogs?

Green is the rarest eye color for dogs. Your dog will have blue or green eyes if the eyes do not create the black pigment eumelanin. In the same way, if eumelanin is not produced in the nose, your dog will end up having a pink nose. 

What is the most common eye color for dogs?

Brown is the most common eye color in dogs. It is the default canine eye color, which is a side effect of the merle gene diluting eumelanin in dogs’ eyes.

Why are dogs color blind?

Technically speaking, dogs are “color-blind” because they only have two color receptors that limit the number of color combinations that they can see (unlike humans that can see a wide range or mix of colors). In other words, they can only perceive certain light wavelengths, which only allow them to see combinations of colors blue and yellow. 

Final Thoughts

Genetics indeed plays a major role in determining our dog’s physical traits and characteristics, including the color of coats and eyes. Thanks to this amazing (yet complex) biological function, all creatures in the world are unique!

Our canine home buddies possess beautiful qualities that can only be dictated by genes. Now that we know why most dogs have brown eyes, we can now see and appreciate them from a whole different perspective.