Good example of sectoral heterochromia in a white domestic cat

This is a beautiful white cat with a not untypical eye colour. It looks unusual but it really isn't that unusual. It is a variation on or an extension of heterochromia iridis in domestic cats which in layman's terms means odd-eye colour. This is what happens.

Good example of sectoral heterochromia in a white domestic cat. Image: Pinterest.

The dominant white gene produces an all-white cat by removing melanin from the hair strands to leave them a sort of opaque-white. The gene affects the migration of melanin producing cells called melanocytes in the iris of the eye.

This can leave the eyes of an all-white cat with the colour blue. This is not because there is blue melanin pigmentation in the iris but because there is no pigmentation. The blueness comes from the refraction of white light through the eye. 

The colours of the rainbow e.g. red, are scattered less than the colour blue as they pass through the eye because they are longer wavelengths. Blue light has a shorter wavelength and is scattered more leaving the eye the colour blue. 

Kittens have blue eyes until about 6 moths after birth as the melanin producing cells create melanin for the kitten's iris.

And sometimes one eye is affected like this and the other isn't which leaves the odd-eyed appearance. This normally means one eye is blue and the other is yellow. And sometimes in the case of sectoral heterochromia that odd-eye colour takes place within a single eye which, means that half the eye is yellowy brown and the other half is blue. Once again this is about the migration of melanin producing cells affected by the dominant white gene.

The dominant white gene also affects hearing. It affects the functioning of the inner ear in the way the nervous impulses are transmitted from the cilia in the semicircular canals to the brain. The theory is the cilia (fine hairs) of the semi-circular canals are missing or partially missing because of the dominant white gene. 

The end result is that the cat becomes either deaf in both ears or deaf in one ear. And if they are deaf in one ear it is on the side where there is a blue eye.

RELATED: Sectoral heterochromia in cats.

Comments are welcome. Wrong? Please tell me.

Mediterranean Cats

Mediterranean cats are often white, short haired, slender, with Van-type markings and sometimes they have odd-eye color because of the presence of the while spotting or piebald gene. The medical term is heterochromia iridum.

Having looked at a lot of cat pictures, the above description is quite typical of Mediterranean cats. I am thinking mainly of the Greek Islands and surrounding areas. That is not to say that a lot of other coat types can't be seen as well. You will see a wide range. It is just that this type is fairly typical. You'll see Van-type cats in Morocco too.

Mediterranean cat - Odd eyed cat - photo by ihasb33r (Flickr)

The above picture is a slightly cleaned up version of the original that was taken on Greece as far as I can tell. It is a nice picture, particularly when cleaned up a bit (my personal opinion). That's why I picked it and thanks to the photographer for the license to publish here.

For me the look is so typical of Mediterranean cats. Quite delicate in appearance and size. That is probably due to the heat. Warmer climates tend to produce smaller cats and colder climates produce larger cats (the Sumatran and Siberian tigers are examples).

The genes that have caused the coat are the same as those that produce the Turkish Van pattern in neighboring Turkey. No surprise there as the countries are adjacent to one another. The picture perfect version of the van pattern is an inverted black "V" shape on the forehead and over the eyes and a black tail.

This little cat has a vestige of that. Blue eyes are due to a lack of pigmentation that was removed by the same gene that removes the pigmentation in the fur - the piebald gene. It is the same gene that produces the painted or piebald horse.

Greek cats are not treated that well it appears. A new cat breed is being created in Cyprus. Also you might like to read about the spread of the various cat breeds from the original source.

Cat Heterochromia Iridum Picture

A cat heterochromia iridum picture or in layperson's terminology a picture of an odd-eyed cat. The photograph was taken by the veterinarians or their associates at the Cuyahoga Falls Veterinary Clinic. This photo has been used with their permission for teaching/educational purposes at www.pictures-of-cats.org (PoC). I want to thank Ryan G. Gates, DVM of the clinic for granting permission. If people want to use the picture please ask the clinic first.

Odd-eyed or odd-eye cats are not that rare. I guess the same can be said about people. White cats and bicolor cats have odd-eyes sometimes. This is because the gene that causes the fur to be white (white spotting gene or piebald gene) can also affect one eye. It removes color in the fur by removing pigmentation, leaving it white, and creates a blue eye. A blue eye is one with a low concentration of melanin which is the pigmentation in the iris of the eye. The way light is reflected and absorbed by the low levels of melanin (a very dark brown color), results in the color blue being visible.

The cat in the picture has complete heterochromia. There are varying degrees of this condition. Read some more about odd-eyed cats and cat eye color. The cat's hearing can also be affected.