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.

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