Overo, Sabino, Tobiano, Rabicano and Splashed White...

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chev

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For those who'd like to know a bit more about colour and how it works in horses, here's a very quick guide....

Some quick definitions.

1. Tobiano

Tobiano is the gene responsible for what most of us know as coloured horses. It causes white patches on the base colour, and is what's called a 'simple dominant' - that means if a horse carries the tobiano gene, it will show tobiano colouring.

Tobianos usually have dark heads, white legs (up to the knee at least), white at the top of the dock and dark at the end, and can have ermine marks, spots, and roaning or bleeding of colour at the edges of patches. The spine is often white (although minimally marked tobianos sometimes have no more than a small patch of white on the neck or shoulder) and the flanks often dark.

Extreme white markings on the face are not down to tobiano, even when they appear on a tobiano horse - they are the result of another gene (or two!).
 

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chev

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2. Sabino.

Sabino is thought to be polygenic - that means controlled by more than one gene. It can be expressed as minimally as one small ragged sock and a white chin, right through loud sabino (where markings are easily confused with some overo patterns) to maximum sabino, which appears white - occasionally with small spots.

There are several characteristics that sabinos show - in order to be classed as sabino, a horse must show at least two of the following;

On legs - ragged white socks or stockings, often ending in a point; knifeblade socks; partial socks or stockings; spots on the legs

On head/face - wide, irregular blaze; odd shaped white on face; lip spots; white chin; white spots under throat

On body - splashes of white on the belly, or extending up the flank or shoulder; odd white patches, especially 'lightning strike' markings; roaning, which can be a little on the belly or flank or cover the body and even head and legs.

This is Tally, who shows the ragged socks that end in points, small white marks on her belly, and roaning at her flanks. Her son also shows sabino characteristics. We has a louder sabino mare - I'll try and find a pic in a while.

Sabino is often better expressed on a red base - so often shows more on a chestnut (or even bay) coat than on black.
 

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chev

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I'm getting there Talou... ;) :eek:

3. Splashed White

Splashed White is, like sabino, usually grouped with overo patterns. It can be extremely striking, or very minimal. Splashed Whites share a number of characteristics with other overo patterns, including very extensive white of the head and white limbs but are different in appearance.

Where sabino markings tend to be ragged, roaned or lacy at the edges, and rounded on tobiano, splashed white is usually very distinct - as if the horse has been dipped in paint. Markings can vary from a white face (blue eyes are common) where just the ears have colour, or a leg that's white to the elbow, through to extensive overo patterns on the body.

Where tobiano patterns tend to start from the top, splashed white starts from the belly and goes up.

Pic shows typical splashed white head - note blue eye - the mare's face could have been dipped in paint. These two also carry tobiano.
 

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wonderpony

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mmm. very interesting. I'm wondering if Indie might be a sabino - will have to go and check those socks tomorrow!

Just wondered why all these names exist and what is the significance of them. Also, why do they all end -ino?

And why you are so interested in them?
 

chev

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Rabicano....

Rabicano is a roaning pattern that can be easily confused with true roan. Like true roan it causes white hair to be mixed in with the base colour, but it also has notable differences.

First is a characteristic tail marking - like white stripes at the base of the tail. Sometimes this is the only indicator.

Roaning, when it occurs in rabicano, is usually more extensive on the hindquarters and flanks. A true roan will have white evenly distributed throughout the body - rabicano is more obviously roan at the quarters, and although the roaning can be widespread, rarely affects more than the quarters, underside, and tail. Shoulders and neck are largely unaffected by the gene..

Rabicano also acts in a similar way to sabino in that roaning is often more marked on the belly and legs. A true roan won't show roan on the legs.
 

chev

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wonderpony - no idea why they're called what they are! I'm interested because I'm basically an anorak that reads too much and should get out more...

And so on to overo.

Overo is the name given to a group of genes that includes sabino, rabicano, and anything else not tobiano! Probably the most widely recognised overo pattern is frame.

Frame overo has several obvious and distinct characteristics.

White does not cross the spine between withers and tail (it can cross over the neck).

Upper legs are generally dark, although there may be white on lower legs.

Head markings are bold and often accompanied by blue eyes.

Markings are irregular and scattered, although tending to be similar on both sides.

Tail is usually one colour.

Frame overo originates in Spanish horses, and is linked to Lethal White Syndrome.

Lethal Whites are horses homozygous for the frame overo gene - that is, they carry two copies. For some reason their intestines fail to develop properly, and the foals die. The only way to avoid this is by not breeding frame overo to frame overo. Because so many patterns including sabino and splashed white can appear so similar, the only way to ascertain whether a horse is a frame overo is through lab testing.

Not all white foals are Lethal whites though - if a foal is born white and survives, there's a very high chance that a combination of genes such as frame and sabino have expressed themselves to the point where base colour is hidden completely.
 

Talou

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Originally posted by chev
I'm getting there Talou... ;) :eek:

So i see!:D
One thing though.....

I still don't understand what rabicano is...:eek:

And what is true roan? Or roan for that matter...Lol...stupid me!:eek:

*Telling myself: Stop asking so many questions Talia!!!*
 

chev

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Rabicano's a strange one - the most obvious marking it causes is the striping at the top of the tail. It looks like stripes on a tabby cat, but they're white. It can also cause roaning, most heavily on the quarters, belly, and legs. Not a very exciting gene really!

True roan is what we would recognise as strawberry roan, red roan and so on. The roan gene is separate to all the roaning caused by the overo group of genes. A true roan will have evenly distributed white hair throughout the body, but the head and legs are unaffected. At least one parent will also be roan - it's a simple dominant, and will be expressed if a horse carries it.

An interesting thing with roans is the way the coat reacts to injury... on a solid coat, hair on the site of an injury will often grow back white. On a roan, it grows back as the base colour, with no white. So scars on a roan can look like stripes of darker hair.

Roaning just describes the way that on some horses white hair is mixed in with the base colour.
 

Nicole5310

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What about Dilutes? surely they fit into the coloured horse category. This is going to get very long.... Can I help?????

There are four main genes that dilute horse coat colours- like adding milk to your coffee....

the CREAM gene,
the CHAMPAGNE gene,
the SILVER gene, and
the DUN gene

Hmm maybe it would be a good time to start with base coat colours... over to you Chev, he he! :D
 

chev

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I've got to sleep sometime you know.... ;) :D

Dilutes.... maybe a new thread for those, since they have a different effect to the pattern genes like those in this thread (Mike is going to love me isn't he?! :D )
 

chev

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No... I would love to but I don't honestly have the brain power. It's just something that really fascinates me. Knew next to nothing about it a couple of years ago, started reading, and just found it incredibly interesting.
 

Bloss

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Wow this is really interesting
:D

So Lottie is a brown tobiano mare although she is black apart from her muzzle, how does a brown one work?

Lottie-


and Cappy??? from what you have said i think he must be a Sabino. I will attach a recent (very bad) picture of him-- i know he is horribly overbent:eek:



I wish i had an older picture of him. He is getting lighter and lighter. He used to be brown with white spots over his back with a almost black mane. He is now 8.:D

edit- sorry the pics are so big-- does anyone know how to resise them
 

chev

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Lottie is a dark bay tobiano - see how her muzzle and flank are lighter? That's dark bay, which is bay with the addition of a sooty gene. Then she has tobiano to give the coat pattern on top of that. She also looks like she has sabino - hence the wide blaze - tobiano won't do that.

Cappy's not a sabino - he's actually a Varnish roan, which is one of the Appaloosa complex of patterns. It's characterised by the roaning and lightning of the coat, which gradually overtakes any other pattern - the bay base with (probably?) blanket spots he had when he was younger, in Cappy's case.
 

Nicole5310

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Sorry Chev, maybe i will start a new thread if anyone wants to know about dilutes.

You know having dilutes, its so frustrating when people dont know the difference between buckskin and dun and they argue black and blue with out having ever found out the facts.

It is such an interesting topic. I too have delved deeply into the world of horse colour genetics just out of interest.:D
 

chev

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Have a look around Nicole - there is, somewhere, a thread on all four dilutes :D

I know exactly what you mean about the confusion though. It's incredibly frustrating when you look at things like Welsh pedigrees and find so many ponies have been misregistered for colour. Makes being an anorak very difficult at times... :D
 
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