A tortoiseshell cat looks at the camera

Breed profile: tortoiseshell cats

Introduction

Tortoiseshell cats (“torties”) have a beautiful and distinctive coat. This makes them very attractive to lots of people.

They sometimes get a reputation for being “naughty torties” and some people think they’re hard to live with.

So, what’s the story behind these enigmatic felines?

What is a tortoiseshell cat?

The first thing to note about tortie cats is that “tortoiseshell” is a description of coat pattern and colour, not breed.

Torties are characterised for having a coat that resembles tortoiseshell. They are usually ginger and black, with either a “brindle” or “patched” pattern. There can be some variation in colour. The ginger can vary from yellow to red, the black can be anywhere from grey to black, these cats are called “dilute tortoiseshell” pattern cats.

Brindle cats have a random spread of different coloured hairs across their coat, they have a “salt-and-pepper” appearance. “Patched” cats have blocks of different colours like a patchwork quilt.

A brindle tortoiseshell cat
A “brindle” tortoiseshell cat
A patched calico cat
A “patched” calico cat

Several cat breeds can come in tortie colours. The most common breed of cat to come in tortie colour is of course the moggy!

The lifespan of a tortie cat is related to its breed, not the coat colour. The average lifespan of cats in the UK is 14 and varies by breed.

Tortoiseshell, calico and torbie coat colours explained

Tortoiseshell cats are black and ginger, but do not have any white on them.

A dilute tortoiseshell patterned cat
Some torties have more muted colours, these are referred to as “diluted tortoiseshell” patterned cats.
A calico cat being petted
Calico cats are tricoloured, they are tortoiseshell cats with white patches.
A torbie cat sleeping
Torbies are tortoiseshell cats who have stripes in their black color patches.

What is “tortitude”?

Torties are renowned for having a unique personality amongst cats which is referred to as “tortitude” (a portmanteau of “tortie” and “attitude”). Torties are sometimes referred to as “the redheads of the cat world”. They are also sometimes referred to as “divas”.

But do torties deserve this reputation?

A survey of cat owners has shown a link between tortie and calico coat colours and “challenging” behaviour. These cats are more likely to hiss, scratch and bite humans. Though it is important to note that cats are rarely aggressive towards humans, they usually behave much more subtly.

Jackson Galaxy of My Cat From Hell fame feels torties are “more sensitive to stimulus around them” rather than being feistier than other cats.

From personal experience working with cats in the clinic I’m not sure whether torties are as grumpy and fiery as some say, but they are usually quite headstrong! Vaccinating tortie kittens is always fun, they are usually very confident and friendly until the injection! Lots of kittens sit still for this but torties always seem to jump or try to nip!

I have a calico cat at home called Lily. She is the sweetest, loveliest cat without a bad bone in her body. She’s a tiny girl, but she’s a firecracker! She likes to run around like a wild animal and she’s definitely the boss of my other cat who is twice as big as her!

My cat, Lily in the garden

Lily is definitely a sensitive soul, she tends to respond strongly to both loving attention and anything frightening. If you give her attention she rolls over, talks, purrs and sometimes drools with happiness. But any sudden moves or noises will send her running for cover!

Genetics of tortoiseshell cats

The genetics of tortoiseshell cats is one of the most interesting things about them (except their personalities of course!).

Cats get their coat colour from the interaction between three genes.

Eumelanin

The eumelanin gene is the gene which controls the production of black pigment. This gene is referred to as “B”. (It also comes in recessive form which creates a brown instead of black pigment).

Orange/red

The orange/red gene determines if the cat will produce eumelanin (ie it can switch off the “B” gene discussed above). In cat where this gene switches off the “B” gene, they produce orange fur instead of black fur.

So how can some cats be black and orange?

The orange/red gene is sex-linked. This means that the gene is found on the X chromosome. Male cats only have one of these chromosomes, so they have either black, or ginger fur. Female cats have two X chromosomes. This means they can have black, ginger or both coloured fur. 

Dense pigment gene

The third gene is the “D/d” gene. When a cat has two recessive (d) genes their coat colour is diluted. This happens because less of the pigment they produce is transported into their hairs.

So how exactly do you get a tortoiseshell cat?

Tortie cats have at least one dominant B gene. This gives them their black colour.

The interesting bit comes with the orange/red gene. Tortoiseshell cats have a dominant and a recessive gene (Oo). In tortoiseshell cats one X chromosome (and by extension, one copy of the orange/red gene) is turned off at random in each cell of the cat’s body. Thus, when their hair grows, each hair is randomly red or black.

Dilute tortoiseshell cats have their colour modified by the third, dense-pigment, gene. Dilute tortoiseshell cats have two recessive (dd) genes.

What about calicos and patched tortoiseshells?

Calico cats and patched tortoiseshells get their patches from a fourth gene called the spotting gene. This gene controls the movement of pigment cells in the developing foetus. 

A calico cat smiling as she sleeps

Patched tortoiseshells have the gene which slows movement of pigment cells causing them to form together in similar colour patches

Calico cats have variable levels of expression of this gene. This gives them varying areas of white fur where no pigment cells moved to.

Male tortoiseshell do exist (but they are very rare)!

In theory, there should be no male tortoiseshell cats. This is because to create both black and orange pigments, there needs to be two copies of the red/orange gene.

The red/orange gene is found on the X chromosome. Male cats have only have one X chromosome.

Usually.

Very rarely (about 1 in 3000) there are male tortoiseshell cats. These cats usually occur because of a genetic abnormality. They usually have an extra X chromosome (XXY). This usually means they sterile and cannot have offspring.

Male torties are very special!

Summary

Tortoiseshell cats are a very interesting a special bunch of cats. 

They have unique genetic makeup. This means that they are always always female, and they can vary on exactly what colour they are.

Tortoiseshell cats are not all one breed, and many different breeds can come in tortie colours. 

People often think they can be “fierier” than most other coat patterns. But in my experience, and that of Jackson Galaxy they are usually just sensitive souls who react to their surroundings.

I love torties. They can sometimes act out, but if you care for them and love them, they will repay your love 10 fold.

lily being cuddled by Emma

Share this post

Share on facebook
Share on twitter
Share on pinterest
Share on print
Share on email

Leave a Comment

Your email address will not be published. Required fields are marked *