Providing care for your daily dose of joy! Serving the Triangle area - based in Durham. A mobile veterinary practice serving the Durham, NC area
02/17/2025
Medical Monday: genetics
Hollywood, Dr. Lorandeau’s family cat, has very distinct color patterns as seen in this picture. Her multicolored coat makes her a “torbie”, short for a tortoiseshell tabby (although she could debatably by a calico tabby!)
Have you ever heard that all calico and tortoiseshell cats are female?
Although it sounds like a trick question, it’s actually (nearly always) true!
Coat color in cats is determined by the X chromosome they inherit from the queen, their mother. This means that in order to be both black and orange, the cat must inherit two X chromosomes, which makes them genetically female.
There are, however, rare cases of male calico cats. These cats have two X chromosomes and one Y chromosome, a condition called Klinefelter Syndrome.
Interestingly, there are some male cats that are have a distinct patch of a “third” color in their coat because of something called chimerism. This is rare condition when two fetuses fuse during development, resulting in the cat having two distinct sets of genetic material. The only way to truly tell the difference between a true male calico or tortoiseshell and a chimera is to perform genetic testing!
