Palomino Genetics

I was chatting to some old friends (not old old; we just go back a long way) and we were discussing chestnuts and their sensitivity, and then started to discuss how palominos can be equally quirky. We could remember that there was a genetic link between the two colours, but after that it all became a bit vague.

I needed to lay my mind to rest, so thought I would share my research with you.

This is genetics at their very basic level, so apologies to any readers who are more versed in it.

All horses start out genetically as either a chestnut, or a black horse. A chestnut horse does not have an extensor gene (so is referred to as ee), whilst a black horse does (so is either referred to as EE or Ee). What the extensor gene does, I’m not sure, but this is after all very basic!

From here, the Agouti gene modifier works on the black horse to create the bay colour. Bay, along with chestnut and black, forms the three basic colours from which all other equine coat colours are derived, with the help of additional genes.

A palomino horse, which is my main focus of this blog, is a chestnut colour (lacking the extensor gene) with one cream dilution gene. This gene causes the red coat to lighten to a yellow colour (anywhere from very light creamy colour, to golden, to an almost chocolatey colour) and for the mane and tail to be white.

Have you heard of the colour “chestnut with a flaxen mane and tail”? This colouring is different from palomino, although they can look similar to the bystander. There is a flaxen gene, which only works on chestnut horses, and lightens their mane and tail so that it is lighter than their body. The coat of the horse is still red, as opposed to the yellowy colour of a palomino.

Equine coat genetics are complicated. I’d like to know more, but even just visually categorising coloured horses into tobiano, overo, tovero gets me in a muddle. I do find it interesting that palomino and chestnut horses have such similar colour genetics, and I’m sure these genes are linked to other genes which contribute to other areas of their personality, giving chestnut mares particularly, a bad name. Perhaps it is that the chestnut coat genes are linked with thinner, more sensitive skin, which can cause problems with ill fitting tack and rugs, or rough handling or riding, which gives the chestnuts the bad name. Perhaps the gene which gives chestnuts thinner skin (don’t ask me where I read that article, but I did whilst researching the chestnut mare myth) is also prevalent in palominos, which could explain why some palominos have that feisty reputation.

Or perhaps it’s just down to the way they’ve been brought up and managed…

Maybe I’ll see if I can find an equine genetics book for dummies to read.

Colour Change

Otis’s cat-friend had kittens last week and they are adorable! Their eyes are just starting to open now, and their ears straighten up.

You may be able to tell that they are a funny colour, almost black underneath with a grey top coat.

Being the geek that I am, and knowing that we will be bringing home the kitten with the white belly, I thought I’d look into kitten colours. 

I found a really interesting article online that spelt out cat colours, patterns and white spotting a for the everyday person – and includes  pictures! Here it is. Because the mum is a tortoiseshell (black base with a red pattern) and I’m pretty sure the tom cat was black, and black is a dominant gene I think the kitten will be black – looking surprisingly similar to our own Princess Penny.

Aside from that, I also discovered that the grey hairs on both kittens are called “fever coats” and occur either when the mother is ill or under stress, or if the particular kitten was under stress in the womb. I know the mother had antibiotics in April for a cold, and because both kittens have it I strongly believe it is a fever coat. After a few months the fever coat is shed to reveal their true colour.

This led us onto discussing the fact that foals are often born a different colour, and change in the first moult. This makes it really hard to fill out the passports, because indeed it is a legal requirement that

You must get the foal microchipped and have a passport before it’s 6 months old, or by 31 December in the year it’s born (whichever is later).

Since 2009 new passports have to be accompanied by a microchip. I hope that the added expense of having to pay for a passport and microchip discourages indiscriminant breeding, and I guess that was the aim of the law. I was also amazed that the fine is unlimited.

One of my Mum’s friends bred a foal a few years ago and he was the most fascinating colour. Almost a dun, he became a lot darker by the time he needed passporting – even the vet didn’t know what colour he would be – and each year since then he has become more roan. Maybe passports, especially with modern technology, could be more easily updated so you can put “current colour” and “predicted colour” when first registering a horse and then, like you do with the lifetime height registration, put “mature colour” or words to that effect. Perhaps there is also the space to update bodily markings because whilst whorls don’t change, scars are acquired over time.

Colour Genetics 

I find colours of horses both fascinating and very confusing, especially when you look at the genetic components. 

Last week I was doing a bit of reading and learnt an interesting fact about grey horses. The grey gene is no so much a colour, but rather a gene that causes the base coat to lighten over time. This explains why grey horses are born black, or chestnut, and start to become grey when they lose their first coat. And also why grey horses have more white on them as they get older.

The other fact I read was that horses are all either a red (chestnut) or black base coat, and it is the influence of other genes that cause such variation. So for example, the effect of the dilution gene can cause a chestnut base coat to become palomino. A different set of genes causes the white patterns over a base coat, as in the case of pintos.

I find Otis quite an interesting colour because to the innocent bystander he is a bright bay. But look closer and you will see a scattering of grey hairs throughout his body. His mane is scattered with white hairs, and he has a skunk tail at the top, which suggests to me that he has another gene acting on his coat, such as one of the roan genes.

Following on from this, someone also told me that breeding some colours together increases the likelihood of having a mutated gene, which can result in cremellos, champagnes, and other colours, which could come with associated health problems. They didn`t go into much detail unfortunately, but with the albino yearling in the news recently I`m sure there will be more research in this area.

Much more interesting to me, though, is the difference between a black horse, and a very dark bay horse. Black is surprisingly uncommon, which I already knew, and people often mistake black horses for dark bays. The key to spotting a black horse is to look at the eyes and muzzle. Here the very fine hairs should be jet black. The eyes of a black horse are very dark brown and the skin is black too.  At this time of year, when the horses are shedding their winter coats it`s very hard to spot a black horse because the winter coat is dying, and is thus a dull brown colour. Additionally, some black horses bleach in the sun which means that the horse loses it`s rich black colour, and they resemble a bay. Black horses that do not bleach are called “non-fading”, or “sheer” blacks. The points of a dark horse can also help identify their colour as well, as true black horses have black points, and no red tinges.


At the moment Llani is losing his coat; so is an iron grey, dull brown on his body, whilst his legs are still black. On his face mis muzzle and eyes are black, but the rest of the hair is sun-bleached and falling out. I can`t wait until he has his summer coat!

With all these complications, it`s amazing that breeders can identify the colour a horse will be when they are born. Passports and microchips need to registered within the first six months, so often breeders have to put their best guess. A friend of mine had a foal from her mare who was born a strange blackish brown colour, which became grey in his first winter, and he seems to have matured as a dun. What complications arise if the wrong colour is put on a passport?  And will we soon see a test to determine the genetic coat colour for horses, rather than relying on the visible signs. Or perhaps the coat colour should be left open to confirmation as a yearling? If there is a commonly available test to prove a horse`s colour it could revolutionise horse breeding, as breeders turn towards breeding rarer colours … but then selective breeding could turn into inter-breeding, and that could lead to a whole host of new problems.

Besides, having inside knowledge about colour genes, reduces the element of surprise!

Black Horses

Earlier this week I took the girls training towards their D+ test round the yard to test them on colours and markings. I felt they should know them so rather than teach they needed to be tested and then the knowledge gaps filled.

Bay and chestnut were easy, and then we found a black pony. “Dark bay” said my victim. I raised an eyebrow. “Well I was told that there’s no such thing as a black horse.” She cried indignantly.

And so began my lecture about black horses.

The trouble I had this week was that most of the black ponies had bleached over their saddle areas. I patiently explained that the coat of black horses bleaches in the sun, some more than others, and usually when they’ve been turned out wet or sweaty. Bleaching can be prevented or reduced by washing and drying the horse fully before turning out and wearing a fly rug or summer sheet.

You can distinguish between black horses and dark bay horses by looking at the skin around their eyes and muzzle. With a black horse this skin is black.

Then one of the girls said “so Ace isn’t black because he’s got white on his muzzle” … Nope. That’s a marking! The Friesian cross is indeed black!

Then we carried on round the yard and came across a couple of dark bays which were correctly identified and then we found another black horse.

“Black” I was informed by one of my riders. “No he’s not!” Interrupted his owner, a more senior pony club member. “He’s bay ‘cos his body has brown bits on.”

I felt like hitting my head against a brick wall. His muzzle was black … And his name was Jet!

Equine Colours

In the hope of not boring you all, I`d like to bring a little bit about equine colours to the table. I was making notes for this Horse Ownership course, and after listing the usual black, bay, chestnut, piebald, skewbald I thought I`d better check for any rare colours.

To cut a long story short I found a site about equine genetics, which touched on cream dilution, my personal favourite silver dapple as well as many others.

The gene which attracted my attention was the Rabicano gene. This gene causes limited roaning pattern in a specific pattern on a horse, and is usually characterised by the “skunk tail” effect, which is when the top of the tail has white hairs. I know one horse who has this feature – Otis.
He`s always had the white tip to his tail, and I`ve always said he`s almost a bay roan due to the speckling of white hairs over his body. So I continue reading this article, only to find that another feature of a horse with the Rabicano gene is sporadic white hairs around the flank and abdomen. Furthermore, the skin of rabicano`s can be mottled with pink, particularly around the abdomen and groin. Guess what! The soft skin of Otis`s abdomen and hind legs is mottled pink, and this gene explains why his barrel is more flecked with white than his neck and legs.

I found this fascinating, as it explains a lot about Otis`s looks.

Upon further reading I found that horses can carry both rabicano and roan genes, but rabicano colouring is rarely extensive enough to be confused with the roan colouring. Additionally, horses can carry the rabicano gene and the sabino gene. The sabino gene causes extensive white markings on the legs and belly (commonly seen in Shire horses) Horses which carry the sabino gene usually have white lip and chin markings. Funnily enough, Otis has a white lip and chin. Now I`m not saying he`s also got the sabino gene as his white markings are fairly conservative, but it`s a definite possibility.

It`s a complex and fascinating topic, equine genetics, so I`d be interested in reading a beginners guide to equine genetics. If there is such a thing of course!

Unusual Names

I arranged for a woman to bring her horse for a hack with her husband and daughters, who rode some of our riding school horses. I was told that the horse was called “Geoffrey”.

So the day comes and I see the horse box arrive, a few minutes later I am introduced to Geoffrey.

I don’t know what image the name Geoffrey conjours up to you, but I pictured a noble bay horse, 16 or 17 hands, hunter type. Perhaps a star on his chiselled face.

So imagine my surprise when a 15hh chunky, fat piebald cob with a hogged mane and feathers.

Does anyone else know any horses which don’t really suit their appearance or personality?

Clever clogs

About a month a go at a dressage competition a heavily feathered cob caught my uncle’s eye.
“what breed is that? ”
“a gypsy vanner. Used to be used by gypsies & usually driven, but are pretty popular as riding ponies now. See the short back? That shows they’re pretty strong.”
A quick description sure enough, but my uncle wasn’t convinced. He googled them at home.

Today I got a text;
“just passed two gypsy vanners”

“Skewbald or piebald?” I ask.

“Newcastle united supporters”

Haha very clever 🙂