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Are All Tortoiseshell Cats Female? Vet-Reviewed Facts & FAQ

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	Dr. Maxbetter Vizelberg DVM Photo

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Dr. Maxbetter Vizelberg DVM

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Like Calicos, Tortoiseshell cats are often said only to be female. Most Tortoiseshell cats are female, but there are rare instances in which a male cat can be born with a tortoiseshell pattern.


What Is the Tortoiseshell Pattern?

a lilac tortoiseshell cat
Image Credit: Alina Vilchenko, Pexels

Cats with a tortoiseshell pattern have particolored coats with patches of red or orange and black. The patches may be fine and speckled or large spots that cover significant portions of the body. Typically, the markings are asymmetrical.

Dilution genes can change the dominant colors to cream and blue, lilac and fawn, or other light colors. Sometimes, tabby patterns with black, brown, or red are seen. Some cats have a “split-face” pattern with black on one side and orange on the other with a defined line.

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Understanding Tortoiseshell Genetics

Leonard Doncaster was a geneticist who first proved the Tortoiseshell is a female heterozygote of orange and black with the corresponding male will be orange.

The primary gene for coat color, B, can be masked by the co-dominant gene for orange color, which comes from a gene in the X chromosomes. Females have XX chromosomes while males have XY chromosomes, which is why both males and females can be orange.

Females, however, are more commonly calico, tortoiseshell, or orange tabby colored, whereas most male cats are orange tabby. In fact, there was a longstanding belief that only male cats can be orange tabbies when it’s just more common. Females have more opportunities to have variations that include the color orange.

Tortoiseshell Pattern
Image Credit: andy-holmes, Unsplash

How Can Males Be Tortoiseshell?

A cat must have XX chromosomes (female) to be a Tortoiseshell cat. Genetic anomalies do occur, however, leading to a cat having three chromosomes. If a male cat has XXY chromosomes, he can be male and still have the required X chromosomes to make a tortoiseshell pattern.

These males are known as Klinefelter males, named for endocrinologist Harry Klinefelter who first identified this condition in the 1940s.

Some male Tortoiseshell cats may be chimeras, which result from fusion during early development with different color genotypes. Some may be mosaics, which means the XXY condition happens after conception, and the cat is a mixture of cells with different numbers of X chromosomes.

In exchange for the rare male tortoiseshell pattern, Klinefelter males are typically sterile from an imbalance of sex hormones. They can’t be bred to produce more male Tortoiseshell or Calico cats, which is in part why these cats are rare to find.

But make no mistake—there is utility in neutering sterile male Tortoiseshell cats. Just because they can’t reproduce doesn’t mean they won’t try to do so. Intact males can develop behavioral issues like urine spraying, territory marking, roaming, and fighting with males. They’re also likely to develop reproductive problems.



There you have it—male cats can be Tortoiseshell cats. Because it’s a specific genetic condition that occurs in XXY cats, Tortoiseshell cats are rare and sterile. Whether you have a male or female Tortoiseshell, however, you can still enjoy a lovable cat with a unique and special pattern.

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Featured Image Credit: andres felipe Aristizabal, Pixabay