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Re: [RC] [RC] More on overos - Barbara ReevesMore importantly, you can get lethal from two FRAME Overos. There is a form of Overo called Splash Overo, and it is not lethal in it's homozygous state. http://www.equinecolor.com has some good pictures to show the different paint patterns. Also, seemlingly solid horses can carry the Lethal White Overo gene. It's uncommon, but not unheard of, to have a Lethal foal born from two Quarter Horses... If you want to breed any stock horse mare to an Overo or Painted stallion, you should make sure he's been tested negative for LW and your mare has too. We recently had as ALL WHITE Sabino Foxtrotter colt born on our farm. He
was bred by the Barn Owner. His momma is a gray mare, bay base, with minimal sabino characteristics (two high socks, a pink chin spot). His sire is a Sabino Roan (black base) with HIGH white socks and a wrap under blaze, but no belly spots. This little guy came out ALL WHITE! Not one spec of color or dark skin on him. Here are a few pictures of him at 1 day old. Any dark spots on him are from mud or dirt. This is one all white occurance that will not be lethal. It is the same gene that causes the all white Thoroughbreds and nearly all white Arabians. There are an estimated 25 or more forms of the Sabino gene. There is a genetic test for one of
them now, but it is not the form that is commonly found in TBs or Arabs, as most obviously Sabino horses of these breeds have tested negative for Sabino-1. More on genetic testing: http://www.petdnaservicesaz.com/Equine.html ~Barbara --------------- [RC] More on overos - Lynn WhiteTitle: More on overosI?m not a
equine color geneticist by any means, but I have read a couple books and talked to breeders. The whole horse color ?language? seems to be regional and meanings change with respect to where one is from. It?s kind of a colloquial thing. To the layman, the term overo can refer to any spotted horse in some areas. When one is talking to an equine geneticist, the three terms of spotted horses (sabino, tobiano, overo) refer to actual genetic makeup. The three types of patterns have three types of genes that can be identified. As stated in a previous post the horse described is most likely a sabino. Many people have sabino horses and don?t even know it?but the tell-tail sabino markings are a white spot on the belly, high leg markings, and a white skinned lower lip. The sabino gene occurs in just about every breed. The overo or tobiano genes on the other hand
do not occur in purebred Arabians or any of the other desert breeds. Someone might have a pintabian with the tobiano or overo gene, but this only means that some ancestor of that horse was a paint or pinto of some other breed. So one would ask (like my husband) why is color genetics so important? The answer lies with what is ?fashionable? (i.e., what will sell) at the time, but more importantly there are color genetic combinations that are lethal. There is the lethal roan and the lethal white. You get the lethal white when you mate two heterozygous overos together and get a homozygous overo (25% probability). The lethal white foal comes with the nasty trait of not having the ability to digest food. So foals are born alive and PURE white but die within a couple days?not a damn thing one can do about it. This is why if you want to breed your colored mare to another colored stallion you really need
to know who carries what genes before you do anything. I personally know two backyard breeders who were unaware of this and ended up with pure white foals that died within two days of birth. The breeders just did not know anything about lethal white, and didn?t ask their vets or pick up a book. I know I?ve strayed from the original post, but I live in ?Paint Country? and look at a lot of colored/spotted horses trying to figure out what the heck they are. My color preference is anything with the crème dilution?buckskins in particular. I also like grullas, but one would be hard pressed to find a grulla that is more than 75% Arabian?I think I?ve only seen one grulla on the endurance trail, and that was a mustang. Only 4% of registered QH?s are grulla. It?s not a common color. Here?s a pretty informative website:
Happy looking, -Lynn
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