How to breed a palomino paint?

[Peace]

Leslie, my trainer, has a cremello mare. I know if she bred her to a chestnut stallion, we'd get a palomino foal. But, if we bred her to a chestnut paint stallion, what would be our chances of getting a palomino paint?

[chev]

If the paint is homozygous for tobiano, 100%. If he only has one tobiano gene, 50%.

[Peace]

Thanks, chev. :) I'd forgotten that tobiano paint is a dominant trait. :) (You got me curious as to why the stallion would have to be a toby - from what I've seen on the Net, apparently it is unclear whether or not overo is dominant or not.)

Let me make sure I understand:

An individual will display the tobiano pattern whether it has one allele for tobiano - Tt - or two - TT.

So even if the tobiano stallion's sire and dam are both tobiano, there's still a two out of three chance the stallion is heterozygous - Tt.

That would mean the only way to know for sure if a stallion is homozygous for tobiano is by way of a blood test?

BTW - Now I understand why Quanah was kept entire for so long. He has the "paw prints" that are supposed to be an indication of homozygous tobiano. :D

[chev]

I forgot about overo patterning :o

Overos are a bit different though; so far no overo stallion has ever been shown to sire exclusively overo foals. Stallions born to two overo parents could sire either 50%, 75% or 87.5% overo foals depending on how many overo pattern genes are present. Overo behaves like a dominant gene; crossing two overos, if the gene was recessive, would produce 100% overo foals. In fact it produces overo, solid and lethal white foals. The unpredictable aspect is the apparent crop out of overo pattern from two solid parents that happens in paint breeding. Overo patterning includes splashed white and sabino patterns too, which does make breeding overo a bit unpredictable.

Genetic testing for tobiano is usually done using a sample of mane or tail hair.

[NZhorserider]

Maybe there are two genes that work to produce the colour?

It would actually be really interesting to work at an equine geneticist (did I just create a job?). I'm sure there are people like this that work with high profile breeders who want probabilities for foal colours.

I want to study biochem and law at uni, this could be my dream job!

Anyone know anything about this field?

Grace :)

[julesandjoy]

There are two recognized types of paint patterns...

Tobiano
and
Overo

W/in Overo there are three different patterns...

Frame,
Splash,
and
Sabino.

Homozygous tobianos have a high chance of colored foals BUT you are NOT guaranteed an outwardly colored foal by breeding a homozygous tobi. There are proven instances where the tobiano gene has been 'expressed' by a short sock or two. The horse has the 'paint' gene but just doesn't show it.

The overo pattern has been linked to something called the OLWS or Overo Lethal White Syndrome. When you breed two frame parents the baby has a 25% chance of being homozygous for the frame gene. A birth defect is inextricably linked w/this gene site and causes death in the foal - usually w/in a week. (It's been a long time since I've read any of this so my time table might be a bit off)

Splash and Sabino patterns could also be homozygous and either one of them could easily be very 'minimal' in outward expression. Sabinos usually have wide blazes and chin white along w/a lacy pattern to the leg white as it continues up into the body.

Splash is my favorite pattern. It looks as though the horse were dipped in white paint as it stood grazing in the pasture! :) The legs are white as will be the nose w/the white coming up to sometimes crossing the topline and the horse could possibly have a completely white head.

To guarantee a pali foal is easy and you'll do so by breeding the cremello w/a sorrel.

Guaranteeing a 'colored' foal isn't as fool-proof. There is still a good bit of luck involved. Maybe just look for a stallion who has a greater instance of colored than non-colored ON SOLID MARES and choose that way.

Either way you go it's a roll of the dice for color. sylvia

[chev]

Homozygous tobianos have a high chance of colored foals BUT you are NOT guaranteed an outwardly colored foal by breeding a homozygous tobi. There are proven instances where the tobiano gene has been 'expressed' by a short sock or two. The horse has the 'paint' gene but just doesn't show it.

I know of a mare who is so minimally tobiano that it's expressed only by a handful of white hair on her dock. She's been registered (and thought of) as solid bay all her life. The tobiano only became obvious this year when she was bred to a solid stallion and produced a nice evenly marked tobiano foal. She is unusual though - usually even minimally marked tobianos will have some white on the body, generally in the form of small 'lightning strike' markings often on the shoulder or quarters.

Tobiano is a dominant gene; if it's there, it'll be visible. Overo, although it has dominant traits, does sometimes seem to appear without the pattern; overo marked foals have been born to parents who had no visible coat pattern.

If a horse tested as homozygous has thrown solid foals I'd be inclined to assume he's not in fact homozygous. The test for tobiano doesn't actually test for the tobiano gene itself - that hasn't actually been mapped as yet. It tests for certain protein markers associated with the gene, along with taking into account a three generation pedigree and coat patterns (pawprints are associated with two tobiano genes for example; but are not exclusive to tobianos). It's possible that until the gene itself is identified that testing may not be 100% accurate.

Sabino is a strange gene. It's extremely common in Welsh ponies, for example; but far less common are the loudly marked sabinos that actually have extensive white patches on the body. Most sabinos will have big white blazes, lip spots, long ragged socks, some roaning, and belly splashes - plenty more have only one or two of those markers. The striking loud sabinos that crop up from time to time rarely throw similarly marked foals, unfortunately.

[julesandjoy]

[QUOTE=chev]I know of a mare who is so minimally tobiano that it's expressed only by a handful of white hair on her dock. She's been registered (and thought of) as solid bay all her life. The tobiano only became obvious this year when she was bred to a solid stallion and produced a nice evenly marked tobiano foal. She is unusual though - usually even minimally marked tobianos will have some white on the body, generally in the form of small 'lightning strike' markings often on the shoulder or quarters.

Tobiano is a dominant gene; if it's there, it'll be visible. Overo, although it has dominant traits, does sometimes seem to appear without the pattern; overo marked foals have been born to parents who had no visible coat pattern."




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A tobi w/o external expression is termed a 'slipped' tobiano. It is possible for a horse to carry the tobi gene and still express no external markings. Overo can hide for generations in a line of horses - that's why it is so important to have your mare and stallion checked for Frame Overo before your breed. OLWS is fatal.
---------



"If a horse tested as homozygous has thrown solid foals I'd be inclined to assume he's not in fact homozygous. The test for tobiano doesn't actually test for the tobiano gene itself - that hasn't actually been mapped as yet. It tests for certain protein markers associated with the gene, along with taking into account a three generation pedigree and coat patterns (pawprints are associated with two tobiano genes for example; but are not exclusive to tobianos). It's possible that until the gene itself is identified that testing may not be 100% accurate."




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One site I visited stated that there have been records of homozygous tobi's w/as little white as a sock or two. And if tobi can be so minimal as to not be distinguishable from solidly marked horses - then why can't a 'solid' foal from a supposedly homozygous horse carry the one gene passed by it's two-gened parent?
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"Sabino is a strange gene. It's extremely common in Welsh ponies, for example; but far less common are the loudly marked sabinos that actually have extensive white patches on the body. Most sabinos will have big white blazes, lip spots, long ragged socks, some roaning, and belly splashes - plenty more have only one or two of those markers. The striking loud sabinos that crop up from time to time rarely throw similarly marked foals, unfortunately."



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I sort of want to think that the loud sabino horses are actualy tovero or at least they would carry two overo genes. A max-white sabino can be solid white and are proported to be the only 'true white' horses. :-) This white colored horse could possibly the expression of a homozygous sabino at work. Or it could be a combination of two, or more, paint patterns.

It's really interesting to try to figure out what pattern a horse has by just looking at them. Some patterns are more or less 'fixed' in their expression, some can mimick another pattern, and sometimes you just have no idea what-in-the-world pattern that horse is carrying!!!! :eek: sylvia

[chev]

A tobi w/o external expression is termed a 'slipped' tobiano. It is possible for a horse to carry the tobi gene and still express no external markings. Overo can hide for generations in a line of horses - that's why it is so important to have your mare and stallion checked for Frame Overo before your breed. OLWS is fatal.One site I visited stated that there have been records of homozygous tobi's w/as little white as a sock or two. And if tobi can be so minimal as to not be distinguishable from solidly marked horses - then why can't a 'solid' foal from a supposedly homozygous horse carry the one gene passed by it's two-gened parent?

That's interesting - I've not found that term, or the theory that tobiano can be carried without being expressed, anywhere in any of the books or any of the sites I've read. Could you direct me to the site where you saw it please? :)

I sort of want to think that the loud sabino horses are actualy tovero or at least they would carry two overo genes. A max-white sabino can be solid white and are proported to be the only 'true white' horses. :-) This white colored horse could possibly the expression of a homozygous sabino at work. Or it could be a combination of two, or more, paint patterns.

Also interesting! There are a huge number of Welsh ponies and cobs who show various degrees of sabino markings, but the occurance of louder markings is still extremely rare. There are a lot of breeders now who actively breed for sabino; and yet still very few loudly marked ponies.

There is no tobiano gene in Welsh ponies at all - so that would rule out tovero patterns. And yet there are still some very typical overo type patterns that crop up now and then in lines known for sabino. They are so rare still that it's not at all common to find loudly marked ponies, even though probably at least half of all Welsh ponies with white markings show definite sabino markers.

I know of one stallion who is almost for sure a maximally expressed sabino. He's white with pink skin, dark eyes, and some areas of pigmented spots under his white coat; and yet to date not one of his offspring have been loudly marked.

[galadriel]

It would actually be really interesting to work at an equine geneticist

There are a couple of universities (at least) that are doing a lot of research into equine genetics. These are the places where you can get equine DNA tested. In the tests that use the results they've gotten so far. And they keep looking for more matchups to try to get more and more specific about what gene correlates to what trait :) If you're itnerested in that field, you can probably contact them and ask what kind of education you need to work there.

Offhand I think U Colorado and UC Davis are leading the field of equine genetics right now (in the US anyway).

[julesandjoy]

[QUOTE=chev]That's interesting - I've not found that term, or the theory that tobiano can be carried without being expressed, anywhere in any of the books or any of the sites I've read. Could you direct me to the site where you saw it please? :)


________________

Why shorely....
I did a simple google search and came up w/these:
**Equine Color - Horse & Pony Color Genetics Information
Sometimes this is referred to as a "slipped Tobiano". There are even horses who have only a couple short socks that test homozygous for Tobiano. ...
www.equinecolor.com/tobiano.html
**Gypsy Horses and Drum Horses for sale
(To date, there is NO direct DNA test for Homozygous Tobiano coloring) Tests ... horses will on occasion produce a solid, also known as a slipped Tobiano. ...
www.gypsydrumhorses.com/sales.htm
**AgDirect - Display Response
... You are getting tobiano (TO), a dominant factor from somewhere. Some tobianos, although rare, will appear to be solid, they are called a slipped tobiano. ...
www.agdirect.com/scripts/ main.exe?2106&8564&11&0
NOTE: This one is just a forum reply but still, the term is mentioned.
**Several more were forum 'mentions' also - you could do a google and research some more.
___________________





"Also interesting! There are a huge number of Welsh ponies and cobs who show various degrees of sabino markings, but the occurance of louder markings is still extremely rare. There are a lot of breeders now who actively breed for sabino; and yet still very few loudly marked ponies.

There is no tobiano gene in Welsh ponies at all - so that would rule out tovero patterns. And yet there are still some very typical overo type patterns that crop up now and then in lines known for sabino. They are so rare still that it's not at all common to find loudly marked ponies, even though probably at least half of all Welsh ponies with white markings show definite sabino markers. "

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Clydesdale breeders try to minimize the sabino expression. They want only white legs and a blaze. Low and behold - sometimes they don't get it!!!
http://www.mustangs4us.com/Horse%20Colors/sabino.htm

That's a pretty interesting site and worth some surfing. I've just now found it but will be exploring for a while!!!!
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"I know of one stallion who is almost for sure a maximally expressed sabino. He's white with pink skin, dark eyes, and some areas of pigmented spots under his white coat; and yet to date not one of his offspring have been loudly marked."


_____________________
WHy is he 'almost for sure a maximially expressed sabino'? Maybe we're describing 'loud' as two different things. A 'loud' sabino, to me, has a wide blaze, four tall white socks, maybe a belly spot or two, and a white chin. A minimal sabino might have a blaze and white chin and nothing else - possibly a short sock. A MAX sabino would be the Medicine Hat expression OR possible the sabino along w/frame... that would give you LOTS of white! sylvia