# Eye color



## Strawberry4Me (Sep 13, 2012)

I believe it comes from the sames genes that cause white patterns, or pink skin. I have seen solid bay or chestnut horses with blue eyes, but they usually have some kind of paint genetics. Like a breeding stock paint could still be solid with blue eyes, or a QH paint cross that is solid bay could still have blue eyes. But I think it is a recessive gene. It doesn't "just happen." 

I could be wrong. I am terrible at color genetics. But this is my understanding.


----------



## dixieandboo (Jan 19, 2014)

I have a paint with blue eyes that have brown patches in them. There kind of freaky looking cause you notice them from a mile away! I think it has to do with there genes. My first horse was a paint and he had one blue and one brown eye.


----------



## kiltsrhott (Mar 11, 2012)

Blue eyes are generally associated with pinto patterns, particularly tobiano, though their inheritance is not entirely understood. Champagne horses will have green or amber eyes. Cremello and pearl horses will have lighter eyes. As far as we know, horses do not have genes that specifically dictate eye colour. Their eye colour is usually influenced by their coat patterns and dilutes, however it is possible there is a gene for eye colour that has not yet been isolated. If there is a specific gene for blue eyes, there is a good chance it is physically near a pinto patterning gene and the mutation for blue eyes occurred in a pinto so now that mutation is often inherited together with the pinto pattern because of their close proximity on the chromosome.


----------



## kassierae (Jan 1, 2010)

Blue eyes are not from tobiano, they are linked to frame and splash. Double dilutes also have blue eyes(cremello, perlino, smokey cream). Champagnes will have a hazely-green type colored eye.
_Posted via Mobile Device_


----------



## verona1016 (Jul 3, 2011)

To add to what's already been said, the blue eyes caused by pinto patterns are generally a brighter blue than those caused by double dilution, and double dilutes can be more green-ish as well. My cremello has one blue eye and one green eye:


----------



## verona1016 (Jul 3, 2011)

There's also an as-yet unidentified gene in Paso Finos that causes light amber colored eyes (called "tiger eyes") in otherwise "normal" colored horses. I'll be interested to see if this study comes up with anything: "Tiger eye" in Paso Fino horses explored - News - Horsetalk.co.nz


----------



## Poseidon (Oct 1, 2010)

kiltsrhott said:


> Blue eyes are generally associated with pinto patterns, particularly tobiano, though their inheritance is not entirely understood. Champagne horses will have green or amber eyes. Cremello and pearl horses will have lighter eyes. As far as we know, horses do not have genes that specifically dictate eye colour. Their eye colour is usually influenced by their coat patterns and dilutes, however it is possible there is a gene for eye colour that has not yet been isolated. If there is a specific gene for blue eyes, there is a good chance it is physically near a pinto patterning gene and the mutation for blue eyes occurred in a pinto so now that mutation is often inherited together with the pinto pattern because of their close proximity on the chromosome.


I have no idea where you got your information, but it could hardly be more incorrect. 

Tobiano definitely does not cause blue eyes. We know that splash and frame do. It is not believed that sabino1 does, but it is the only mutation of sabino that is isolated currently, so it is uncertain if other mutations can cause blue eyes. 

Cream also causes blue eyes when homozygous. Perlino, cremello, and smoky cream will always have blue eyes. 

Champagne horses commonly have greenish or amber eyes.


----------



## Strawberry4Me (Sep 13, 2012)

What is it that causes blue eyes in Shires?


----------



## Peppy Barrel Racing (Aug 16, 2011)

Cream can also make golden eyes too! This mare is color tested palomino. Like said the only know white patterns that cause blue eyes are frame and splash. Double cream also causes blue eyes.

_Posted via Mobile Device_


----------



## kiltsrhott (Mar 11, 2012)

Poseidon said:


> I have no idea where you got your information, but it could hardly be more incorrect.
> 
> Tobiano definitely does not cause blue eyes. We know that splash and frame do. It is not believed that sabino1 does, but it is the only mutation of sabino that is isolated currently, so it is uncertain if other mutations can cause blue eyes.
> 
> ...


This info came out of an old equine coat colour genetics book. It's Jeanette Gower's book from '99. I think what's happening with the phrasing here is that it's referring to "wall eyes", the single or partial blue eyes found in most pintos, as something different than the two complete blues of the splash. Here's a quote directly from the book "Wall eye is possible in a total solid, but I have only seen it in ponies of tobiano ancestry." It also contains a chart listing characteristics of each pattern and blue eyes is included under the list of tobiano characteristics. She seems to imply that tobiano strongly influences the wall eye factor in a few locations in the book. I, personally, have only known two paints with blue eyes and both were tobiano. Perhaps the reason there are higher numbers of tobiano horses with wall eyes might be because there are more tobiano horses in general? It is the most common pinto pattern, after all. It could be possible these horses have other patterns at play, yet to be isolated, that have influenced their eye colour, but who am I to argue with this woman's observations? I have not written a published book on horse coat colours, nor have I done extensive research on my own. I'm sure some of the info is outdated, but I don't think it's entirely untrue.


----------



## NdAppy (Apr 8, 2009)

It is extremely rare for a horse to be tobiano and nothing but tobiano (in regards to white patterns).


----------



## Chiilaa (Aug 12, 2010)

Additionally, Jeaneatte Gower's book, while it was fairly comprehensive at the time, is 15 years old now. That is a significant amount of time that has passed, and it is not at all surprising that current theory does not match hers. 

The researchers who isolated the tobiano gene do not believe it causes blue eyes.


----------



## kiltsrhott (Mar 11, 2012)

> It is extremely rare for a horse to be tobiano and nothing but tobiano (in regards to white patterns).


I find it hard to believe that tobiano without sabino, splash or overo is "rare". I could see this being true among certain lines of paints, but it's not hard to find tobiano stallions that have been genetically tested to be heterozygous or homozygous tobiano and test negative for other patterns (at least for what we can test for). A horse cannot be homozygous tobiano and also sabino as these are mutations of the same gene. Splash in itself is rare This leaves overo, which is commonly tested for because of lethal white syndrome and though it is not an uncommon pattern, many paints do test negative for it.



> Additionally, Jeaneatte Gower's book, while it was fairly comprehensive at the time, is 15 years old now. That is a significant amount of time that has passed, and it is not at all surprising that current theory does not match hers.


I agree. The chapter on appaloosa patterns is particularly outdated and disproven. However, Jeanette's book says nothing about tobiano causing wall eyes. I never said it did either. I just pointed out that it is often seen in conjunction with it (and with other pinto patterns too). I actually theorized that there is another gene at play here that we have yet to isolate (which seems to be the consensus on the internet save for splash which seems to do its own thing). There are many tobiano, overo and sabino horses with brown eyes, and solid horses with blue eyes. This leads me to believe that none of the pinto patterns _cause _the wall eyes, but that wall-eyes are the result of another mutation originally occurring in a white-patterned horse, hence why wall eyes seem to be most prevalent amongst pintos of certain lines.

I just did an extensive google search and the most recent article with some valid sources that I could find on the topic is from 2006 with quotes from Sponenberg that say "what is understood about blue-eye inheritance is tied to breeding results and logical guesswork". There really is no current research beyond Gower's. It's all just speculation at this point, as no specific cause has been isolated.


----------



## Chiilaa (Aug 12, 2010)

kiltsrhott said:


> I find it hard to believe that tobiano without sabino, splash or overo is "rare". I could see this being true among certain lines of paints, but it's not hard to find tobiano stallions that have been genetically tested to be heterozygous or homozygous tobiano and test negative for other patterns (at least for what we can test for). A horse cannot be homozygous tobiano and also sabino as these are mutations of the same gene. Splash in itself is rare This leaves overo, which is commonly tested for because of lethal white syndrome and though it is not an uncommon pattern, many paints do test negative for it.
> 
> 
> 
> ...


Splash is in no way "rare". Two of the strains that have been isolated are only in certain Paint/AQHA lines, but the other type has been found in many horses already, and the test is a very new one. The researchers that isolated the genes involved in splash have already said they feel there are more splash strains that are yet to be found. 

The same goes for sabino - there is at least one more white pattern that we haven't isolated that causes a "sabino" like effect, and it is likely to be a KIT loci mutation, due to the way it presents. 

Current understanding is that blue eyes are tied to a few white patterns. Most people, plenty of whom are in touch with current research, believe that blue eyes are tied to both Frame and Splash. Occasionally, someone talks about it being tied to sabino too, but that is yet to be supported with any evidence.

As well as this, a true "solid" horse is exceedingly rare IMO. The amount of solids that get tested for white patterns are minuscule, which means we cannot rule out white patterns being there. For example:

This mare has a son who tested homozygous for splash 1 - which means she has to be at least heterozygous.









This stallion also has a son who tested homozygous for splash 1. I believe he is completely solid under the blanket, but don't have an image of him without it.









This mare has a son who has been tested to be homozygous tobiano. This means she has to be heterozygous for tobiano. She is the most minimal marked tobiano I have ever seen. She is also a silver black, and her mane and tail is silver, not white.









This guy has been tested and confirmed frame positive. He has no white - but very striking blue eyes.


----------



## kiltsrhott (Mar 11, 2012)

What you just stated doesn't disprove anything I just said on the blue-eye front. The argument was that blue eyes are somehow linked to overo and sabino as we know it and not tobiano, and I don't think it is, because you can find plenty of examples of horses with blue eyes that test negative for these patterns.

I don't disbelieve that there are things we don't understand at play here. This what I've been trying to say the entire time. The inheritance of blue eyes is just not yet understood. There are more recent articles, and even what's been posted in this thread is just full of speculation, but no solid evidence of anything.

Tobiano is the most common _observable _pinto pattern in the horse population, hence why there seem to be quite a few tobiano horses with blue eyes. If you're asking this question based purely on observation, this statement holds true.

Just because you can find a few examples of solid horses that have tested positive for pinto patterns proves only that pinto patterns can be expressed very minimally. We already knew this, hence the occurrence of "crops outs" which have been a struggle for breeders to understand for centuries. Not once did I deny that, but something tells me this is not the norm. I still stand by the assumption that if I tested my entire barn for the whole panel of pinto patterns, I would not find many unexpected positives on the solids.

I'll pull up a few more examples:










Here's a mare with blue eyes that tested negative for tobiano, frame, and sabino. She still has blue eyes. This leaves splash open as a possibility but there's no proof of it. All this disproves is that blue eyes must somehow be linked to overo and sabino.

You linked quite a few examples of horses that test positive for splash but don't have blue eyes and one that tests positive for overo and _does _have blue eyes.

Here is a horse with characteristic blue eyes and potential splash markings but he tests negative for splash.










Here are a few more of the same splash negative with blue eyes:




























This was all found through some research within the Morgan breed which also found a lot of minimally marked splash positives, some with and without blue eyes. Honestly, the only conclusion I can draw looking at this data is what I said in my first post, which was "it is possible there is a gene for eye colour that has not yet been isolated".

Though I must thank you for challenging me on the splash statement because I had no idea studies were being done on minimal splashes. I did just learn a lot about splash in the last few hours (though not much more light has been shed on the blue eye issue). Perhaps I will test my own horse for splash and see what happens. She does not have blue eyes, but she does have a crooked, bottom-heavy face marking, 4 high stocks and a belly spot, but she tested negative for sabino 1. Instinct tells me she expresses a form of sabino not yet identified, but it would be fun to try the splash since it's available to test for.


----------



## Chiilaa (Aug 12, 2010)

Just because a horse tests negative for one of the currently isolated white pattern genes doesn't mean there is no white pattern gene present, just that there is no KNOWN AND ISOLATED gene present. When you think that 20 years ago we couldn't test for any colours, and now we can test for so many, it is hardly inconceivable that there are more to be found. 

I am not saying that there is not something else acting. There HAS to be something that is switched on to create the blue eyes, because not all splash or frame horses have them. However, I don't believe it is as simple as another gene that is specifically for eye colour - there is no evidence of it being anywhere near hereditary enough to suggest that it is a gene on its own. More than likely it will end up being something that only acts when a large checklist of genes are present.


----------



## Chiilaa (Aug 12, 2010)

I just looked at your horse. She does look sabino to me, and not splash. However, of course she tested negative for sabino 1. It is very well known that it is pretty much pointless to test for sab 1 unless your horse has Tennessee Walker or Miniature heritage, as most other breeds have some other sabino form, not sab 1.


----------



## kiltsrhott (Mar 11, 2012)

I completely agree with you Chiilaa. I'm not entirely sure why this has turned into an argument of sorts when neither of us has really said anything that contradicts what the other one has said. Didn't I just say in my last post, that I think my own horse expresses a white pattern that has yet to be isolated? There is much more research to be done, and somehow, I think there always will be. Genetics is complicated stuff. I also don't think there would ever be only one gene responsible for eye colour alone. It is known that the genetics for human eye colour are way more complicated that just one, simple gene. More than one cause for blue eyes in dogs has already been found. It would not surprise me at all if horses were the same way or even if a whole complex of genes were involved, hence why I've been using the word "possibility" a lot in my wording. Even Jeanette Gower seems to think this in her book written 15 years ago. When I said "gene for eye colour", I was referring to a common denominator amongst most blue-eyed pintos, that "switch" you speak of that will help us start piecing together the puzzle and understanding how its expression works. I was only trying to argue that I don't think the possibility for blue eyes is restricted to overo, and splash as we know it, which seemed to be a consensus among a few, and from what I can tell, you seem to agree with this.


----------



## kiltsrhott (Mar 11, 2012)

Yeah, I had her tested because it's not expensive and I figured it can't hurt to know! I have read that the sabino expressed by draft horses is not sabino 1, and I'm pretty sure it's her draft side of the family that gave her those markings, but I don't actually know her pedigree. I say she's a Shire/TB because that's what I was told and I think she looks the part, but she's not registered and supposedly her parents weren't either. I think her negative sabino 1 result only further proves my suspicions that she expresses whatever form of sabino is prevalent in shires and clydes. It might be fun to try the splash though. It's a long shot but why not?!


----------



## wakiya (Feb 7, 2009)

verona1016 said:


> There's also an as-yet unidentified gene in Paso Finos that causes light amber colored eyes (called "tiger eyes") in otherwise "normal" colored horses. I'll be interested to see if this study comes up with anything: "Tiger eye" in Paso Fino horses explored - News - Horsetalk.co.nz


There are also tiger eyes among cream horses in Spanish Barbs


----------



## Lockwood (Nov 8, 2011)

There is always my horse who didn't read the rule book. I've been meaning to have him tested just because I'm curious. He's a buckskin and his right eye is amber and green. 

It's really hard to catch him with his eyes open wide enough to see it really well, but the top third of the eye blends into a very striking icy green color, getting lighter and lighter as it goes up.

The left eye couldn't make up it's mind which color it wanted to be...blue or dark amber. 
Both eyes combined makes for a very expressive horse. :lol:


----------



## Robynpleigh (Feb 15, 2014)

Scout is on loan to me well part loan and he has one blue and one brown eye and he is a piebald
_Posted via Mobile Device_


----------



## Poseidon (Oct 1, 2010)

kiltsrhott said:


> Tobiano is the most common _observable _pinto pattern in the horse population, hence why there seem to be quite a few tobiano horses with blue eyes. If you're asking this question based purely on observation, this statement holds true.


The problem with this statement is that you're only looking for tobiano because it is the most expressed on a horse of that situation. This does not account for facial markings, which tobiano is not believed to cause at this time. We have posted pictures in another thread of minimal frame overo horses and Chiilaa has posted minimal splash. I would be willing to bet that any of those blue eyed tobianos also test positive for another pattern. In the off chance that they don't, UC Davis would probably want to keep that DNA on file for further research into gene isolation.


----------



## Zexious (Aug 2, 2013)

Such a cool thread! We have so many well informed people on our forum. <3

Lockwood, he has such pretty eyes.

/GoesBackToLurking


----------



## Saltybaby (Feb 12, 2014)

What about gold and blue- upper eye is actually goldish, but the lower part of the eye has small patches of blue.


----------



## Breezy2011 (Nov 23, 2012)

I have a purebred quarter horse with one blue eye... I don't know where she gets it from, because both parents are pure quarter horses


----------



## Poseidon (Oct 1, 2010)

Breezy, I know we've told you this before in other threads: quarter horses carry splash and frame, both of which cause blue eyes. Truth be told, she could be either or both. The snip could be splash and her star could be frame. If you want to know, test her; the most you'll spend is $50.


----------

