Odd Eyes in Cats (Heterochromia)

Once in a while, you'll see a cat with a striking condition called heterochromia iridis, which means irises that are different colors. Also known as odd-eyed cats, these lovely kitties have two different colored eyes. They typically have one blue eye, and the other is either green, brown, or yellow.

Cats with two different colored eyes are usually white or have some white areas on their bodies. The same gene responsible for their white fur coloring controls their eye color. Kittens are born with two blue eyes and over the following weeks, melanin moves into the iris and causes a color change to green, yellow, or brown. In odd-eyed cats, this only occurs in one eye; the other remains blue.

Sometimes a bit of melanin moves into one iris but doesn't completely change the eye's color. That iris will have some blue in it as well as some other color such as green.

The cause of odd eyes
Odd eyes can be inherited from parents (genetic) or acquired due to certain illnesses, injuries, and medications. Acquired odd eyes cannot be passed on to the kittens. However, most commonly, odd eyes are congenital (associated with development defects).