I’m honestly a bit disappointed in the “spotless”, but otherwise, excellent foals we got this year. We bred two loud overo TB mares and one pure white ISH mare, all by our beloved Puchi’s Rambo (near 100% color produced on only solid mares) to our very flashy, obviously sabino TB stallion (pretty blaze and 4 high, jagged stockings). We got three big, stunning, loveable, correct conformation foals…but no overo markings…NADA!! One colt has a crazy ? mark blaze and three stockings, another has just a star/strip and the third has stockings to the knees and hocks and a pretty blaze. I’d never be sorry for “correct”, healthy foals, but must admit that I’m shocked by the lack of overo markings.
So my question is…I know the genetics a totally different, but do sabino’s bred to non-homozygous tobianos have any higher chance of “spotting” than any other color patterns?? I know the tobie is stronger than overo and I’ve never crossed the two, but just wondering. This year we have one overo TB and two tobiano ISH’s bred to the flashy TB stallion. I’m not complaining, but I hate to face life, “spotless”!!
Nope. It’s still 50/50. The “KIT” gene handles Tobiano, The various Sabino/Whites and Classic Roan colorings, and it’s a straight 50/50 sort of thing.
One thing to note, Puchilingui was Dominant White, not Sabino/Overo. He was the founding “W5” horse. If your mares’ coloring is coming from his white it’s W5, a modification of the KIT gene, not OLW. I don’t know what lines your stallion comes from, but if he also comes from white lines you may run the risk of non-viable embryos by pairing White and White. It is suspected, though not confirmed, that homozygous White foals are non-viable and the pregnancies are terminated in the early stages.
But stockings to knees and hocks ARE “over” markings 
Same with the ? marking and 3 socks. Technically they all are “overo” markings, just some more normal/common than others.
Were you looking/hoping for body white?
Tobiano is tobiano and works independently of any Overo pattern, though they can merge and hide each other. There are very minimal Tobianos with only a wither spot and low socks, and there are very loud Tobis. All the Overo patterns can be very minimal or very loud, depending on zygosity and just luck of the draw.
Sabino x Hetero Tobiano has a 50/50 chance of having Tobi spotting. If Sabino is passed, it may or may not make itself known. Any time you breed 2 patterns in their heterozygous state, you have a 75% chance of at least 1 of them passing on. The question then becomes - will it be visible. With Tobi, yes, with rare exceptions. With Sabino, pretty much a crap-shoot.
Puchi’s Rambo was Dominant White 
W5, though Puchilingui. Which other stallion are you referring to? Is he a son of Jagged Illusion? If so, also W5, but depending on the dam line, possibly also another version as well.
The combining of W variants leads to interesting results. Some combinations produce only normal markings, where others produce wild results. I’ll come back with the collage of tested W horses to show you how some of them combine.
[QUOTE=Twisting;7677251]
It is suspected, though not confirmed, that homozygous White foals are non-viable and the pregnancies are terminated in the early stages.[/QUOTE]
Some of the Ws yes, some no. There are confirmed HZ Ws, so we know at least some are not embryonic lethal
Here’s a W20W20 horse
http://colorgenetics.info/equine/gallery/white-patterns/white-spotting-formerly-dominant-white/w20/jango-homozygous-w20
Here’s a good description of each W variation that I had not seen yet
http://www.tawnyhorse.com/?page_id=170
and if you click on “see images” at the bottom of that page, then you’ll see the gallery I was looking for with tested W horses, some of whom are hetero for just 1, some are homo for 1, and some are hetero for 2 different ones
What do you mean by overo? Have you had them gene tested? True overo is a heterozygous genotype (homozygous is lethal white). Therefore overos have a 50/50 shot at passing that on.
You say tobiano later in your post, so I’m not sure which you mean. Twisting is correct in saying that KIT handles tobiano coloring, while OLW is for overo coloring.
Sabino is also separate from overo- SB1 gene. SB1 is a mutation of KIT as well; SB1 homozygotes can be nearly or completely white.
There are some horses with “high white” that don’t carry the SB1 gene. It’s not really known exactly what causes this, but is due to changes in migration of neural crest cells during development and may be as much environmental/ congenital as anything.
Do sabinos crossed with non-homozygous tobianos have a higher chance of spotting? Maybe. Let’s say the stallion is a SB1 +/- and the mare is Tobiano T/t. So they’re both heterozygotes. Your foals will come out:
±Tt sabino, tobiano (probably mostly white or all white)
±tt sabino, solid (high white but solid body)
–Tt not sabino, tobiano
–tt solid
You’d have to check with a punnett square, but I think those are all equally likely.
What if the stallion’s sabino is not caused by SB1? Well, chrome tends to throw chrome but I don’t know exactly how heritable that is.
What if the mare is homozygous tobiano? Then all the foals will be tobiano.
I have a question as well: is it possible for a horse to carry the tobiano and the overo gene? What does that look like?
To make things very easy to understand, as well as being much more correct, one should use Frame for what you are talking about Frame is one of the overo patterns. Overo is just “non-tobiano”, so it includes frame, sabino, splash, and the (dominant) white patterns.
There are some horses with “high white” that don’t carry the SB1 gene. It’s not really known exactly what causes this, but is due to changes in migration of neural crest cells during development and may be as much environmental/ congenital as anything.
Lots of DW (they are trying to start calling these just White, but they’ve been called Dominant White for a while, so…) also cause high white on the legs as well as face white. The newest discovered (ie testable) DW pattern looks like it might well be one of, if not the, original ones - found in very old breeds.
Do sabinos crossed with non-homozygous tobianos have a higher chance of spotting? Maybe. Let’s say the stallion is a SB1 +/- and the mare is Tobiano T/t. So they’re both heterozygotes. Your foals will come out:
±Tt sabino, tobiano (probably mostly white or all white)
±tt sabino, solid (high white but solid body)
–Tt not sabino, tobiano
–tt solid
You’d have to check with a punnett square, but I think those are all equally likely.
Yep - 25% chance of nothing passed, 25% just Sabino, 25% just Tobi, 25% both.
I have a question as well: is it possible for a horse to carry the tobiano and the overo gene? What does that look like?
Again, “overo” is a broad term If you mean Frame, then absolutely it’s possible, which is what led some group of people years ago to loudly proclaim that Tobianos could also produce a LWO foal :rolleyes: What they look like highly depends on how loudly or minimally each pattern is expressed. I do know that Frame + splash tends to magnify the white, but I don’t know if that happens with frame + tobi as well.
I have a question as well: is it possible for a horse to carry the tobiano and the overo gene? What does that look like?
yes - that’s called a “Tovero”
My friend wrote this book that is just coming out:
http://www.amazon.com/The-Equine-Tapestry-Introduction-Patterns/dp/0990475921/ref=sr_1_2?ie=UTF8&qid=1405982420&sr=8-2&keywords=equine+tapestry
She writes very clearly about spotting patterns, and you might find it useful for a general overview of how horses can be spotted. (She also writes a lot about the history of these various genes through different breeds.) She blogs at http://equinetapestry.com
Daylene is a wealth of knowledge, and I look forward to getting her book!
WOW!!! You guys are great…but the information is overwhelming!!!
First…mares are all sired by our Puchi’s Rambo (by Puchilingui, o/o Copper Anna (chestnut mare with some white) I know Puchi is dominant white, but for simplicity purposes we’ve always called our produce “overo” versus tobiano and there are no frame characteristics. We have produced some “whites”, but IMO they are just max white bays and chestnuts (red or black bonnets at birth.)
We have never crossed our Rambo mares to a tobiano stallion…we got plenty of color out of Rambo.
Our current stallion is “Challenged” - Unbridled’s Song o/o Money Madam by AP Indy. No color in that family tree that I’m aware of. http://www.pedigreequery.com/challenged We have not had any LWO’s to my knowledge…Rambo was only bred to solid mares and Challenged was bred to three mares who each produced a live foal.
I do follow “most” of your explanations, but…can I expect to ever get loud overo body white (or whatever you want to call it…) in future breedings to the same mares?? Are these sons and daughters able/likely to pass on “color”?? How do horses with “just plain chrome” stockings, etc. vary from W5??
Thanks… so far!!
Is Challenged the “pretty blaze and 4 high, jagged stockings” stallion? If so, that’s a lot of “color”
Some stallions are “white killers”, so even with mares who produce a lot of color with another stallion, they can produce minimal white.
However, given his white markings, it would be more surprising for him to produce a hoard of white, than to produce what he’s produced, unless it was the mare who did it.
AP Indy does have some white to his pedigree (look at Secretariat), but nothing like the Puchi line white, so you’re not likely for him (Challenger) to be the source of a lot of white. Most likely what’s going on is he’s more likely to produce high whites, or multiple white legs, with face white, than allow a boldly marked foal. It’s very possible these particular mares will push enough white to have more wildly marked foals.
The other factor is these KIT mutations are attached to Extension, so if the mares are Ee, then the extent of their offspring’s white markings will be linked to whether their DW is attached to the E or the e. If it’s to E, then they will produce louder black-based foals than red-based (since the e won’t get the DW along with it), but if they’re attached to the e, then they can produce loud markings on either color, since it would be the stallion at that point who determined if they were red-based (ee) or black-based (Ee).
What color are the 3 foals in question here?
JB, how do you know what Extension the DW is linked to? Is it different for each horse, each DW variant (e.g. W5, D15, etc), or is it ‘unknown until it’s known’ by looking at a number of offspring from one producer etc?
DNA testing could likely tell, from an “in the lab” standpoint, you wouldn’t be able to tell from the current style of DNA test results.
Not to mention that the link isn’t 100%. It is very very common for the two things to go together, they are on the same chromosome after all, but every once in a blue moon chromosomes like to get funky and tangled themselves up and switch things around.
And yes, you still have a 50/50 chance of getting dominant white foals from your dominant white mares. Now, expression levels, that is a smidge more complicated. Extension can effect that (red is louder than black based) as well as who knows what sorts of other factors determine expression levels. We haven’t figure out all of those yet.
Twisting, I ask because I have an all-white DW mare. She is the product of a new mutation from non-DW parents/lineage. She is the world’s first (only) DW studbook Hanoverian. Genetically she is chestnut with no S1. She is (was born) all white with 4-5 small pigmented spots along her crest and dock.
So far, testing has not been able to pinpoint where on the KIT gene her particular mutation has come from. I would love to get a better handle on this, as I would love to be able to test for DW in her offspring. She has had one foal (a bay colt with long socks and a very wide blaze by a stallion with similar markings).
Are you saying that I have more chance of getting a loud/all-white foal if I encourage chestnut offspring?
She is currently in foal to Furstenball due October.
A chestnut who is also DW obviously has the DW attached to one of the e’s, but obviously you don’t know which one, and even if you did, it’s still a 50/50 chance that e will get passed each breeding. But all that means is that she can produce loud Ee and loud ee foals, whereas the horse with the DW attached to the E (assuming hetero) only has the chance of producing the loud black-based foals.
Red-based colors do typically allow more white expression of the other overo patterns. But, because the Ws are showing that combinations, and HZ status of some of the numbers usually result in a very loud production, I don’t know how much that holds true for these. Puchilingui was obviously very loud, bay, and hetero for W5. On that chart, there’s another bay/brown who is also W5/+ and very minimal. There’s a hetero W19 black-based who is pretty loud, then the HZ W20 looks like a fairly minimal Splash with a bald face. So…shrug
I know Tobiano is typical attached to E, but I don’t know if there is a known pattern of attachment, ie W5 to E but W20 to e.
Link breakage/crossing is about 7%, meaning if you have enough breedings, 7% of the E/To links will break and you’ll get To and e passed
[QUOTE=JB;7677820]
Is Challenged the “pretty blaze and 4 high, jagged stockings” stallion? If so, that’s a lot of “color”
Some stallions are “white killers”, so even with mares who produce a lot of color with another stallion, they can produce minimal white.
However, given his white markings, it would be more surprising for him to produce a hoard of white, than to produce what he’s produced, unless it was the mare who did it.
AP Indy does have some white to his pedigree (look at Secretariat), but nothing like the Puchi line white, so you’re not likely for him (Challenger) to be the source of a lot of white. Most likely what’s going on is he’s more likely to produce high whites, or multiple white legs, with face white, than allow a boldly marked foal. It’s very possible these particular mares will push enough white to have more wildly marked foals.
The other factor is these KIT mutations are attached to Extension, so if the mares are Ee, then the extent of their offspring’s white markings will be linked to whether their DW is attached to the E or the e. If it’s to E, then they will produce louder black-based foals than red-based (since the e won’t get the DW along with it), but if they’re attached to the e, then they can produce loud markings on either color, since it would be the stallion at that point who determined if they were red-based (ee) or black-based (Ee).
What color are the 3 foals in question here?[/QUOTE]
Yes, Challenged is the flashy stud…dark brown, blaze and 4 high, uneven/jagged stockings. The mares/foals are this:
- Chest/white loud overo = dark brown (shedding to black on body, but not black) big ? mark blaze, two high stockings, one med, stocking, one white spot on heel. Looks like he tried to bolt/duck when they applied his “white”!!
- Dark brown/white loud overo (full sister to Jagged Illusion) = very dark brown, no leg white, odd reverse ? star, strip on face.
- Totally white with one 3"x3", colored spot on her windpipe. We always assumed she was bay based because she had black skin/hairs at poll. Spot looks “bay”. Guess not…she had a bright chestnut (haven’t had a chestnut in 10 years!) with a symmetrical blaze, stockings right to the knees and hocks. This is a 3/4 TB, ISH. Others are TB.
What is “KIT”??
KIT is the name of the gene who’s variations are responsible for many of the white patterns found on horses. Tobiano, Sabino, Dominant White (your girls) and Classic Roan are all variations of the KIT gene. Just as Extension is the name of the Black/Red color base and Agouti is responsible for Bay/black.
Overo typically refers to the Frame gene these days, and is a different gene all together. Calling them Overo is something you might want to avoid. Frame is lethal when homozygous, and causes foals to die of colic within hours/days of birth due to a malformed digestive tract. It requires testing and special considerations should be made when breeding to avoid the potential for a homozygous foal. The chances of your horses having the Frame gene is slim to none.
Girl number 3 might very well be a bay. Just because chestnut bases tend to show white more than black bases doesn’t mean you can’t have a maximally expressed bay. It’s just a tendency. If she is bay, then her chestnut foal being non-white suggests the W5 gene is linked to black in your horse. Which is actually a bit odd, because Sato is a palomino W5, suggesting W5 is linked to chestnut. Maybe that 7% crossing chance is coming into play.
Sounds like you just got unlucky and none of your girls passed on their color. Though white can be pretty minimally expressed, so there is a small chance one of them is hiding white.
[QUOTE=Twisting;7678614]
KIT is the name of the gene who’s variations are responsible for many of the white patterns found on horses. Tobiano, Sabino, Dominant White (your girls) and Classic Roan are all variations of the KIT gene. Just as Extension is the name of the Black/Red color base and Agouti is responsible for Bay/black.
Overo typically refers to the Frame gene these days, and is a different gene all together. Calling them Overo is something you might want to avoid. Frame is lethal when homozygous, and causes foals to die of colic within hours/days of birth due to a malformed digestive tract. It requires testing and special considerations should be made when breeding to avoid the potential for a homozygous foal. The chances of your horses having the Frame gene is slim to none.
Girl number 3 might very well be a bay. Just because chestnut bases tend to show white more than black bases doesn’t mean you can’t have a maximally expressed bay. It’s just a tendency. If she is bay, then her chestnut foal being non-white suggests the W5 gene is linked to black in your horse. Which is actually a bit odd, because Sato is a palomino W5, suggesting W5 is linked to chestnut. Maybe that 7% crossing chance is coming into play.
Sounds like you just got unlucky and none of your girls passed on their color. Though white can be pretty minimally expressed, so there is a small chance one of them is hiding white.[/QUOTE]
I know about frame…wouldn’t touch one with a ten foot pole for breeding stock…but APHA calls the lacey colored/white pattern that our horses possess “overo” and registers them that way. What would you call it?? They are white based with lacey black/brown/bay/chestnut (only one) colored hair. I’d like to know the current reference “label” for future discussion. Why do you mention Sato?? Our line goes from Puchilingui to Puchi’s Rambo to our mares…no palomino/Sato connection. His palomino must have come from his dam. No relation here, just same grandsire. If the “white” mare is actually bay as we thought…how did we get a chestnut baby?? There are no chestnuts in Challenged’s family line for a long way!!! I know it is a recessive gene, but for how many generations??
Thanks for all this info.
Another thought…do any of you experts have any thoughts on whether a stallion has any greater influence on “color genetics” than the mares?? Rambo sired almost 100% colored foals of many breeds - TB, QH, WB all solid mares. Jagged Illusion sired two colored foals o/o one solid bay/brown TB mare and a 1/2 TB, ISH mare…solid dark brown, no white. 2 for 2 =100%. We now only have daughters of these two stallions and the mares are not as prolific with their spots!! Just poor luck??
Crosscreek, it may pay you to make a cup of tea and settle into reading one of the many well-written equine colour genetics blogs. The info may be a bit dry but just chew off a bit at a time! As a breeder of coloured horses, this is something you need to get to grips with.
The correct name for your horse’s colour is Dominant White. Recently there is a push for it to be just called White (even though most White horses are not actually all-white). Most people still refer to the old name of Dominant White. It is confusing and incorrect to call it Overo (regardless of the papers from APHA).
The base body colour e.g. bay, black, chestnut is determined by Extension - there are only two, e is red and E is black. E is dominant over e.
So a horse that is ee is chestnut. Bred to chestnuts it will produce ONLY chestnuts.
EE is dominant black based. This horse be black, brown, bay or any shade in between. When bred it will produce ONLY black-based horses, either bay, black, brown etc.
Ee is also black-based (E) but carried a chestnut gene (e). The black is dominant therefore the chestnut gene remains ‘hidden’. The horse may be any shade of black, bay, brown but can have chestnut offspring. When crossed with a chestnut horse there is a 50/50 chance of chestnut foal. The ‘hidden’ chestnut gene can be passed through endless generations.
It seems that this year was just bad luck re the lack of colour, but I too, am keen to know whether DW is sex-linked.
