How do you explain the changing hair colour pattern of a tabby cat?
Some cats have fur that changes colour along its length
This week's question comes to us from Mary Murty in London, Ontario. She asks:
Each strand of hair on my tabby cat has a series of colours along its length. How does each follicle produce a hair that changes colour as it grows?
Tyler Jordan, a Canadian PhD student in the College of Veterinary Medicine at North Carolina State University says tabby cats have what is called an agouti type hair colourization pattern. This means that individual hairs are composed of different bands of colour.
It is common in animals and is due to cells known as melanocytes that are located in various parts of the body, including hair follicles, skin and eyes, of both animals and humans. Melanocytes manufacture pigment known as melanin which give colour to skin, eyes and hair.
There are two main types of melanin; one that produces varying shades of brown to black pigment, and another that produces varying shades of yellow to red pigment. Specific shades of melanin that are deposited in growing hairs and how those pigments are layered on top of one another give an animal's hair its distinct colour.
In the agouti type hair, melanocytes located in hair follicles go through cycles where they alternate between producing different shades of melanin that are then deposited within the growing hair itself. This results in the distinctive colour bands that are found on the hairs of a tabby cat.