Piebald in Cats
White spotting grades
Eye colors + colloquial terms
EYE COLOURS White, or mostly white, cats often have blue eyes, amber eyes or one of each colour. Non pedigree white, or mostly white cats, may have green or yellow eyes. Non-pedigree colour & mostly-colour cats can have eyes any colour, but rarely blue eyes. In pedigree cats, breed standards define which eye colours are allowed.
Geneticist terms
Unusual patterns (developmental)
(Brindled Bicolour) Due to failure of one of the pigments in a red/black tortoiseshell.
Roan patterns
Salt-and-pepper pattern, most striking in black roan. Associated with Karpati gene and Lykoi gene.
Dominant mutation from Eastern Europe (Poland, Romania), variable roan effects including "reverse colourpoint" effect.
Found in Finnish feral colony, 2007; Identified 2024 as mutation of white spotting gene.
Tabby-style pattern seen in supposed feral cat, resembling snow leopard clouding. Authenticity not confirmed.
Age/health related
Early stage - isolated white spots.
Later stage - Cobweb/Snowflake effect progressing to solid white.
Fur around the eyes becomes pale, giving spectacled effect.
Fur may grow back white.
May be greying of fur around muzzle.
"Thai" white spotting gene (skunk stripe)
The Thai White Spotting pattern includes a white dorsal stripe and a white tail that may have a band or blotches of black. In Thailand, the pattern is called But-Se-Weis or But-Tal-Lon and various degrees of white—all with a dorsal stripe—are depicted in manuscripts. These patterns can also be seen in native Thai cats. The diagrams below show some of the variations.
Theories of how white spotting works - DISPROVEN
Theory 1: The melanoblasts arise from the neural crest (the back of the embryo) and migrate over the body when the skin forms. If melanoblasts don't reach their intended position before the skin is fully formed, those areas of skin won't have pigment producing cells and will be white. This is why white is most often found on areas furthest from the neural crest: paws, belly and chest. Areas closest to the neural crest—the back and tail—are most likely to get pigment cells.
Theory 2: A cellular mechanism reduces the melanoblasts in certain areas. Melanoblasts first migrate over the whole surface of the embryo. At the extremities, they selectively die out (apoptosis) or are biochemically turned off. The dying off/turning off spreads towards the torso. How far it reaches depends on a chemical gradient that is strongest at the extremities, but gets weaker further away. The white belly area is the embryonic ventral seam that expands rapidly during growth.
Theory of how white spotting works - PROVEN
The White Spotting gene affects the embryo melanoblasts which become pigment-producing skin cells (melanocytes).
Theory 3: For high grade white spotting there may be another mechanism that produces jigsaw-like patches. First the melanoblasts migrate evenly across the skin surface. Then the expanding skin surface "cracks" during early embryo growth. Cracks break up the coloured surface into islands. The islands drift apart over the embryonic surface as the embryo grows. White areas form between the coloured islands. The white areas are like scar tissue and there are no more melanocytes available to fill them in. Some islands can get pushed together to create a mask-and-mantle pattern. It's similar to how continents moving on the Earth's surface. The white belly area is the embryonic ventral seam that expands rapidly during embryo growth (or it is the limit of melanocyte migration). Black feet are black islands that get pushed to the foot extremity by the expansion of the belly region the same time that limbs were forming.
CREDITS TO MESSYBEAST CATS
