Guide to Horse Color Genetics

Horse Image Template by Cat-Orb-Shop
Guide by lXxMellodyxXl

Additional Materials

This Site will tell you the genetically possible colors of offspring of two horses based on the parents’ genetically based coloring.

This Flash Game on dA will allow you to test out what different gene combos look like on a horse.

This Off-Site Game will teach you about various horse genes and allow you to test them out in a similar interactive feature.

Writing Genotypes

In many cases the Roan gene is written as Rn instead of simply R in the genotype of a horse. Either case works. In fact, you’re perfectly welcome to use whatever letters you want when you’re writing a genotype as long as it has been clearly defined somewhere what genes your letters correspond to. The ones listed here are simply those I found most common, and were undoubtedly chosen because they resemble the name of the gene.

Naming Phenotypes

A phenotype is the physical appearance of any particular gene, and in horses most of those appearances have a specific name. For example, a horse with a genotype Ee/aa/DD is a black dun, a phenotype commonly called a grullo. However, the exact same coloration may also be called a grulla, or a mouse dun, or simply black dun. My main point is that there are alternate names for many of these colorations, and so long as they refer to the correct genotype they’re all right.

One phenotype of particular note is the silver gene on a black horse. It is listed here as Silver Dapple (because I’m American). In other parts of the world, this color is more commonly known as Taffy or Chocolate. It’s the same color and same genotype, just a different name.

Genes and Horse Breeds

This guide isn’t necessarily meant to reflect actual horse breeds, merely to explain the various genes present in domestic horses as a species. However, not all of these genes are possible or present in all horse breeds, and some are undesirable in certain breeds. For more information on the possible colors of any specific breed I suggest you look that breed up. I can however mention one specifically, that is the pearl gene.

As mentioned in the guide, the pearl gene is extremely rare, made more so by the fact that it is a recessive trait. This gene is believed to have originated on the Iberian Peninsula (otherwise known as Spain and Portugal), and is only seen in breeds such as the Lusitano and Andalusian, which are native to the peninsula, and in the American Paint Horse, Quarter Horse, and Peruvian Paso, all of which have Iberian ancestors. In short, you need a very specific kind of horse to get a pearl (in the real world).

Wait, Mellody! You got something wrong!

That is not surprising. I am not a horse geneticist, breeder, owner... Frankly I have no contact with horses except on extremely rare occasions, and this has been the case my entire life. Between that and my lamentably incurable humanity, there are undoubtedly mistakes in this guide. And since I don’t really want that, please let me know if you see any!

Spelling mistakes are easiest. Just tell me and I’ll fix it as quick as I can so no one else sees my lame spelling errors.

If you see any issue regarding the specific genetic properties mentioned in this guide, let me know. However, I ask that if you have such a correction to make that you also provide me with some proof that you know what you’re talking about. This is nothing against any of you, I just want to make sure this guide is as scientifically accurate as possible. The best way is to direct me to a study that has been made on whatever subject you’re correcting, but if you have credentials as working professionally on horse genetics in some way we can work with that.

If there’s a problem with any of the images or descriptions in this guide, let me know. Again, I will need some proof that I’m wrong. Several pictures of actual horses might persuade me, or an online resource. We can work that out.

I will not be replying to every comment made to this image.

I will respond to questions asked. I will respond to suggestions or corrections. I will not say “thank you” to everyone that posts a compliment or thanks.

Not because I’m ungrateful, because I am very grateful and I hope people will find this helpful and attractive and all that jazz. Know that I do see these comments, and any favorites, and I appreciate them. So to save time and space, THANK YOU ahead of time.


Edits!
8/1: After further research, the white genes in the guide have gotten a major rehaul. Roan, gray, and rabicano have been moved in with the white genes where they ought to have been. Dilutions and modifiers have been combined as they all change the base color of the horse. The genes of the KIT locus have been grouped together as they should be. The leopard complex images have been rehauled to be prettier and more accurate and to include a very interesting effect Lp can have on black pigment. Toveros have been nixed as being a misrepresentation of white paint genetics, and a new guide explaining various gene combinations will be made. Also, will probably make a guide to the twenty-odd "white" KIT genes that have been discovered since the advent of DNA analysis.