[Animals] How and why do Siamese cats change color?

[FNX Magokiler]

With 73 cat breeds recognized by the International Feline Association, it can be difficult to distinguish a Ragdoll from a Ragamuffin.

However, most of us can spot a Siamese cat. The Siamese is one of the most easily recognizable breeds in the world, known for its dark eye masks, socks and patterns, called "points," that stand out against its cream-colored body and bright blue eyes.

These characteristic points are due to a genetic mutation known as the Himalayan gene, which was discovered in the breed in 2005. This recessive gene, passed down from both parents, also gives cats a temperature-sensitive coat that can change color.

In the womb, Siamese develop at a temperature of about 38 degrees Celsius, the normal temperature for a cat. Once born, all-white Siamese twins begin to get colder on their extremities, such as their tail, paws, ears, and face. These lower temperatures cause the Himalayan gene to activate the body's melanin, a pigment also found in people. That's why the bodies of warmer Siamese cats remain light, but their cooler parts darken as they mature.

"You can see how they change," says Betsy Arnold, a veterinarian who runs an exclusive cat practice in Rochester, New York, and who began breeding Siamese cats as a teenager.

At two weeks old, Arnold says, the dark hues begin to spread to her extremities.

 

 

Around one month of age, its final color appears, which can be one of several varieties, including the blue point, the lilac point, the chocolate point and the seal point, which has a light cream-colored coat with dark brown nuances in the legs, tail, nose and ears.

A lifelong influence
The Himalayan mutation occurs naturally in domestic cats from South Asia, says Leslie Lyons, a feline geneticist at the University of Missouri (United States) who first identified the mutation in Siamese cats.

Over time, selective breeding of strikingly pale, dark-tipped cats passed the gene on to different breeds, such as Siamese, Ragdolls, and Burmese. Mixed breeds can also carry the genetic mutation.

The vibrant blue eyes of these cats are also due to the Himalayan gene, which influences the pigment in their eyes.

The Himalayan mutation causes the coat to darken as the cat ages, although any type of trauma or change to the cat's coat can alter its shades.

For example, if a Siamese cat undergoes surgery, an area of fur that has been shaved may darken again because the affected area is cooler while the hair grows back. Over time, the coat may become lighter again, Arnold says.

In the 1920s, a Siamese cat living in Moscow who wore a jacket over a shaved shoulder grew white hair again, as that area stayed warmer. Later, the fur darkened again, according to the University of Alaska.

 

https://www.nationalgeographic.es/animales/2023/10/gatos-siameses-como-por-que-cambian-color