Heterochromia in cats: why do some cats have bicolor eyes?

Heterochromia in cats is when the eyes are of a different color. But what causes it, and in which breeds is it likely to occur? Find out more about this anomaly.

If you have ever thought you saw a cat with different colored eyes, don’t worry, it wasn’t the product of your imagination. They themselves have a wide variety of colors. However, you may never have heard of the term heterochromia in cats: why do some cats have two-colored eyes?

Heterochromia in cats: when it occurs 

In people you will rarely have observed this anomaly, an anomaly that is much more frequent in cats . Variations and unusual color combinations range from  a blue eye and a gold eye, to a green eye and a blue eye . 

Heterochromia occurs in cats when a gene for white spots , linked to coat color, blocks the distribution and concentration of pigment in the iris during development. That is why it is more common to see this irregularity in white cats or cats with a certain white in their fur . 

The gene that makes the cat’s fur white is the same gene that gives them their unique eye color.

There are two types of heterochromia:

  1. Complete heterochromia : A cat has two different colored eyes.
  2. Partial or sectoral heterochromia : one color predominates in the iris of one eye.

Why is heterochromia common in cats? 

Heterochromia in cats begins when they are babies . For example, kittens are born with blue eyes. Its true color shows between 7 and 12 weeks of age. There the pigments in your eyes, known as melanin, initiate the change . 

The gene that creates white fur prevents melanin from reaching one of the eyes during kitten development. This obstruction causes melanin to develop and move to only one eye, leading to two different colored irises. 

In cats that have sectoral heterochromia, melanin does not spread completely in one eye, leaving it partially blue .

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Could any cat have two-colored eyes? 

In general, it is very common to find cats with  heterochromia . What’s more, any feline could have different colored eyes  since many have white parts in their hair. Naturally, white cat breeds will be the most prone to this anomaly ( here are four of them ). 

Cat breeds that tend to heterochromia are:

  • Persian .
  • Siamese .
  • Don Sphynx .
  • British Shorthair .
  • Cornish Rex .
  • Devon Rex .
  • Turkish Van Cat .
  • Munchkin .
  • Japanese bobtail .

Are there dark-coated cats with heterochromia? 

It is very rare for cats with dark or black fur to have two-colored eyes . It is more common to find it in completely white cats or in those that have some white fur on their coats.

What is the rarest eye color in cats? 

The rarest cat eye color is the dichromatic or diachronic eye that is regularly seen in white cats. This is when there are two colors in a single iris . The colors usually vary from blue to yellow, going through green, orange and brown . Also, it can change in tone and intensity.

What eye color is dominant in cats? 

The dominant eye color for adult cats ranges from greenish yellow to gold . In most breeds of cats, various eye colors were possible. This led the breeds to establish a specific eye color that harmonized with the coat color and positioned it as the standard for that breed.

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Are green eyes rare in cats? 

Green eyes are often the eye color most associated with cats and it is perhaps not a coincidence that they are often related to luck and mystical powers. Legends aside, green eyes are quite common , especially in mixed breeds.

Are cats with heterochromia also deaf?

It is a myth to think that cats with different colored eyes are predisposed to be deaf cats . Most of these kittens, up to 70%, are not deaf . In contrast, 10-20% of cats with eyes the same color are born deaf or will become deaf when they are grandparents. 

If a white kitten has a spot of any other color on its fur coat, this reduces its chances of being deaf.

On the other hand, white cats with at least one blue eye are more likely to be deaf . The target gene can affect the cochlea shortly after birth.

It remains on the table that heterochromia in cats is more common than we think . Despite this, there is still something mysterious about these special-eyed felines that continues to fascinate cat lovers.


Divyesh Patel