Cats’ color, gender connected genetically
I read your recent column about eye color in cats, and it piqued my interest. I have two orange female kittens, and my vet said it was uncommon for female cats to be orange in color. Is that correct? Why is it the case? I heard calicos are always female, so I suppose there must be some kind of connection between sex and color in cats. Is this also true in dogs? I also heard something about the possibility of sterility in certain cats with certain color and sex combinations. Any truth? In cats, genetics are definitely involved with color combinations and gender of the animal. There are many genes involved in determining color, and there is close linkage to the ultimate gender of the kitten. Color genes are not typically associated with gender in other mammalian species, including dogs, to the best of my knowledge, but as you probably know, birds and reptiles often have more color expressed in the male. Your veterinarian is right. About 81 percent of orange cats are male. Orange females occur only if the orange gene is on both x chromosomes, which means that both of your kittens’ parents had to be orange as well. When it comes to calicos or tortoiseshell color, they are always female. The rare incident of a male at 1 in 3,000 is usually sterile due to a developmental anomaly. If a calico female mates with an orange male, half of their female kittens will be orange and half of the male kittens will be orange, and the rest black. Cats have a sex linked orange/red gene known as O/o that determines the type of melanin or color produced, of which there are two predominant types. Eumelanin is for brown/black color and phaeomelanin sets the orange/red color. This color gene is located on the x chromosome. There are many other genes in cats that determine for hair coat patterns, length, density or dilution of color, such as the agouti gene for stripes, tabby gene, ticked gene and the KIT gene that leads to white cats. This is a lot of confusing information but interesting, and I hope I answered your questions.