The Feline Eye(s)

Feline Eyesight: Day and Night

Eye Color and Genetics:

Eye Color in Felines

Eye color in felines, like many traits, is influenced by multiple genetic factors. Some genes directly influence eye color, while others have indirect effects. The primary driver of eye color is the distribution and density of melanin within the iris. Here’s a breakdown of the nuances of feline eye color and the genetics involved:

Cats' eyes are blue as kittens because they haven't developed the melanin pigment yet. Most will change to a different color as they grow, but some cats retain this blue hue.

Blue eyes are generally associated with a lack of melanin in the iris, leading to the scattering of light in a way that makes the eyes appear blue.

Certain breeds, such as Siamese, have a genetic predisposition to blue eyes. The gene responsible for the Siamese coat pattern, a form of partial albinism, also affects eye color. This gene is referred to as the Himalayan gene or the cs allele.

Green eyes in cats are the result of a medium amount of melanin in the iris.

It is not entirely clear which specific genes result in green eyes, but it is a combination of genetics, the scattering of light, and the type and amount of melanin present.

Breeds like Russian Blue are often associated with green eyes.

Gold and yellow eyes are due to a higher concentration of melanin than found in green or blue eyes but not as much as in brown eyes.

The richness and depth of the gold or yellow hue depend on the amount of melanin present.

Again, the specific genes responsible for these colors are not entirely clear, but it's known that melanocyte-stimulating hormone (MSH) can stimulate the production of melanin, thus influencing eye color.

These eye colors are similar to gold but may have a deeper hue due to the presence of more melanin.

Breeds like the British Shorthair might exhibit these colors.

Brown eyes in cats are less common than in humans. When they do appear, it's usually due to a very high concentration of melanin.

Breeds like the Burmese are associated with deeper eye colors.

While many genes affecting coat color in cats have been identified and studied in detail, the exact genes and mechanisms behind all the nuances of feline eye color are not yet fully understood. In many cases, breeders rely on empirical knowledge – that is, they know that breeding two cats with certain characteristics often results in kittens with certain eye colors, even if the specific genetic mechanisms are not clear. As genetics research continues, more insights will undoubtedly emerge about the intricate dance of genes that determines a cat’s eye color.

What are common genes that can cause blue eyes in feline?

In addition to the genes mentioned above, it's essential to understand that the genetics of feline eye color is complex and still not fully understood. There are likely other genes and modifiers at play that haven't been identified or studied in depth. The interaction of multiple genes, as well as environmental and developmental factors, can contribute to the eye color outcome in individual cats.