In Oriental breeds of cats such as the Siamese and the Himalayan, the color of the fur is defined by the temperature of their skin. The skin is a bit cooler at the body’s extremities such as the tail, feet ears and face, feet, which is why they have white or cream-colored bodies and darker points. Nevertheless skin temperature isn’t the only determining aspect. The temperature of the cat’s environment can have a comparable effect: Many Siamese cats get darker in the chilly winter months in northern regions.
It is strange, but true, dark-colored cats can get bleached out in the sun. If your cat spends a lot of time outside, or if she/he spends her time lying in sunny areas indoors, his/her coat may lighten.
A diet undersupplied in the amino acid tyrosine can cause black cats’ hair color to turn from black to reddish. Tyrosine is needed to process melanin, the dark pigment in cat fur, and if a feline doesn’t get enough tyrosine in her/his diet, her/his ebony fur may fade. Other nutritional problems such as zinc excess and copper deficiency can cause black fur to lighten as well... Be sure to check with your veterinarian before giving your cat any supplements, however, because a change in fur color could also point toward thyroid, liver, or kidney disease.
As cats age, they start getting gray hair just like humans do. However, if your kitty is dark in color, you probably won’t observe the silver strands stealthily moving in. The fur of seal-point Siamese and other dark-pointed Oriental breeds moreover darkens with age. Siamese kittens are born white and only begin to build up their colored points once they’re outside their mother’s womb, so this occurrence is in all probability a continuation of that process.
Keep in mind always at any time you’re unconfident about something that’s going on with your cat, your best resource is your trusted veterinarian.