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.

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