Six Things You Didn’t Know About… Your Cat’s Coat
Every time I spot a cat on Instagram that has the same colour coat as Lola (technically ‘snow bengal’ although it’s more a splodgy mix of coffee and cream!) I instantly assume that they must have the same personality – mischievous, chirpy and affectionate.
Now I come to think of it, I don’t just have these knee-jerk associations with cats that look like Lola. I’ve been carrying around other stereotypes too, like thinking of orange cats as bold, cheeky chappies – and black and white tuxedo cats as sophisticated, thoughtful souls.
But does a cat’s coat really mean anything at all?! Or are appearances really just skin deep? And where do our cats’ wonderful array of colours and patterns come from?
In this week’s post we go down the rabbit hole to discover the surprising secrets of our cats’ coats. It turns out, they can tell you a whole lot more than you ever imagined…
White cats are white…right? Well, yes – but that’s not the end of the story.
It turns out that every white cat has a secret colour! This is a colour that they have inherited from their parents, and can pass onto their kittens, but which is temporarily being masked by a ‘whitening’ gene.
So what colour is your white cat really? Well, you could puzzle it out using some knowledge of genetics if you knew what colour their parents were, or if they have a litter of kittens (if you’re curious about a specific case, just leave me a message in the comments below or email me at firstname.lastname@example.org, and I’ll do my best to use my distant memories of university genetics to work it out!).
But there is also another pretty amazing way that your white cat might reveal its secret colour. When a white cat is a kitten they very often develop a patch of coloured fur on their head. This patch is their ‘true’ colour! It could be ginger or black… or any of the other cat colours. But as the kitten grows their whitening ‘mask’ will kick in fully and the coloured patch will disappear (Robinson, R. 2013). Time to get the kitten photos out and see if you can catch a glimpse of your white cat’s secret colour!
2. CALICO / TORTOISESHELL CATS ARE ALMOST ALWAYS FEMALE, AND ORANGE CATS ARE OFTEN MALE
It might surprise you to know (it did me) that there are really only two varieties of colour in a cat: black and red. Those colours can be ‘diluted’ by the action of other genes, to produce lighter shades such as grey (diluted black) or apricot (diluted red) but black and red is pretty much the palette you have to play with!
The crucial thing when it comes to gender is that the black/red gene is carried on the X sex chromosome. Males are XY so they only have one copy of this chromosome (and therefore are either black OR red), but females are XX so they have two copies, which means – with the right parents – they could be black AND red.
All across the animal kingdom, including in cats and humans, having females wandering around with double the amount of ‘X’ stuff than the men get isn’t a great scenario. So biology has taken care of the situation with a bit of a bodge: each cell in a female’s body gets to randomly switch one of its X chromosomes off.
In a female cat that has inherited a ‘black’ from one parent and a ‘red’ from the other, this process will result in a patchwork of cells each randomly choosing whether to produce black or red – giving the characteristic dappled two-tone of a tortoiseshell cat!
It’s because of this strange quirk that only* females can be tortoiseshells. As for calico cats, they are just tortoiseshell cats that have a version of the whitening gene that acts in splodges, giving them white, orange and black patches. So all calico cats are females too! (Cummings, M. 2006)
(*if you’re being very strict a male cat who accidentally ends up with an extra X chromosome could be a tortoiseshell or calico cat too, but this XXY scenario is very rare and a cat like this would almost always be sterile).
In ginger cats the situation is a little bit different. Both males and females can be orange, but because of the way that they are formed, male orange cats are three times more likely to be produced in a litter than females (Robbins, N. 2012).
Why? The orange gene is on the X chromosome, so a male cat only needs to inherit one orange gene from his mother to be an orange cat himself.
By contrast, for a female cat to be completely all-over orange, she needs to end up with an orange gene on both of her X chromosomes, which means her father needs to be an orange cat AND her mother needs to have been either completely orange or have had some orange in her (tortoiseshell or calico). This is a more unlikely scenario than the one for males, and as a result, the ratio between orange males and females ends up at around 3:1.
3. YOUR CAT’S COAT HAS A BEARING ON THEIR PERSONALITY
Does the way that your cat looks have any influence on their personality? In 2016 a fascinating study asked several hundred cat owners to describe their cat’s appearance and then complete a behavioural profile for their cat.
Were any of the traits linked to appearance? Amazingly, yes!
They found that…
- Agouti cats are more likely to be aggressive (Agouti is a gene which if switched on makes your cat’s fur produce its colour intermittently, so if you hold an agouti hair up to the light, it will appear coloured in bands. A non-agouti cat has solid colour all along the shaft of its hair).
- Orange cats are more likely to be interested in prey
- Piebald cats are less likely to be aggressive towards strangers (Piebald just means white patches combined with another colour, e.g. black or tabby).
- and Siamese and Tonkinese-patterned cats (aka ‘pointed cats’) are more likely to experience separation anxiety.
Of course, these are just associations – not all orange cats will be interested in prey, and I’m sure you can find the odd piebald cat that has a violent streak when it comes to strangers!! Nevertheless, it’s fascinating to learn that some cat differences aren’t just skin deep.
The big job for the scientists now is trying to unpick why these trends exist! Nobody knows quite yet, but it’s probably not ‘orangeness’, for example, that is making orange cats interested in prey. Instead, it’s much more likely that the orange gene lives near to a version of a gene that influences hunting behaviour, and since they’re close neighbours they often tag along together for the ride down the generations!
4. POINTED CATS CAN CHANGE COLOUR WHEN THEY GAIN OR LOSE WEIGHT!
Pointed (or ‘colourpointed’) cats are those like Siamese, Ragdoll, Tonkinese and Birman cats which have lighter bodies, and darker faces, feet, tail and ears.
This unique colouration comes from the fact that these cats have a mutation in one of their enzymes involved in making melanin, which makes the enzyme a little bit finnicky about temperature! In the central parts of a cat’s body, it is warm enough to deactivate the enzyme, so melanin isn’t produced and the fur appears lighter. However, by the time you get to the cat’s extremities it is cool enough for the enzyme to leap into action and start a melanin-producing factory.
What I find most amazing about this process is how it changes over the cat’s lifetime. Pointed kittens are born uniformly white, because the temperature of the womb is high enough to completely switch off the enzyme. They’ll then darken over their lifetimes, with their ‘final’ colour dictated by the conditions of their environment – cats in warm climates or that live in very warm houses end up paler in colour than cats that live in cooler places!
Finally, if your pointed kitty puts on a few extra pounds, you might also notice their points darken a few extra shades. That’s because the fat acts as an insulator and makes their skin temperature just a little bit lower than when they were thinner. (Jerold, B. et al. 2012)
5. CATS DO GO GREY, BUT MUCH MORE SLOWLY THAN WE DO
Have you ever noticed how difficult it is to spot an elderly cat? Tilly, pictured above is my mum’s cat, and at the ripe old age of 16 she’s apparently the equivalent of an 80 year old in human years. So where are all her grey hairs and wrinkles?!
It turns out that the speed at which an animal goes grey is related to the number of pigment producing cells (called melanocytes) that they have in the first place. That number can differ by individual, by species, and even in different parts of the body. For instance, the reason that humans tend to go grey at the temples first is because we start off with the fewest melanocytes there, so we have less to lose!
Nobody knows quite why cats seem to grey so slowly, but it has been suggested that maybe they start off with more melanocytes in the first place. However, they’re not completely immune to greying. Even the most sprightly elderly kitty is likely to sprout a few grey hairs, often on their face first, and they’ll be the easiest to spot if your cat is a dark shade such as black.
6. CATS CAN CHANGE COLOUR FOR ALL SORTS OF REASONS
We’ve already seen the wonderful way that temperature can influence coat colour in pointed cats. But all cats can change their coat colour – and for a variety of reasons – some completely benign, some a signal that they need a trip to the vet. There are so many that we can’t list them all here, but here are some of the most intriguing colour-changing causes:
- Summer / winter coats: It’s not just pointed cats who change colour depending on the temperature. All cats’ coats are influenced to a greater or lesser extent by the temperature. It’s quite common for cats to be darker in winter and lighter in the summer!
- Fever coat: This is a temporary lightening of the coat, most commonly seen in kittens born to mothers who have had a fever or experienced stress during pregnancy. It can turn a kitten’s black coat silvery grey, or a light coat a few shades lighter. The good news is that it isn’t permanent – when the hair is shed it will grow back its normal colour.
- Black coats with a reddish tinge: Too much time in the sun can bleach a cat’s jet black coat, but a coat with a reddish tinge could also signal that your cat has a deficiency in an amino acid called tyrosine – which is essential for the formation of melanin. If you spot this happening, it’s worth checking in with your vet, who will be able to give them a check up and may suggest some changes to their diet.
That’s it for this week’s post. I’d love to hear if there are any questions about your cat’s coat that you’d like to have answered – or any genetic mysteries I can help you untangle!
Just leave me a comment below, or join in the conversation over on Instagram or Facebook (@supakitstore).