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KeralesBC,

The fact is that it's possible for a merle dog to not appear merle, hence the term "hidden" or "cryptic" merle. It could have one tiny merle spot somewhere on its coat that goes unnoticed. It's still a merle though. As far as the original poster is concerned hidden merle likely isn't a concern, but since it DOES EXIST, I would have been remiss in not mentioning it, especially given how popular merles are.

 

So while you're right in saying a dog can't carry a merle gene without expressing it, the degree of expression, or lack thereof in case of a hidden merle, is what's at question.

 

J.

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just wondering, but how do you get a merle if you cant breed two? i know there are genetic problems with breeding two but all this talk of breeding merles and colours has made me curious. im not thinking about breeding im just a bit lost with all this.

thankx

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Merle is dominant. So merles carry either one or two merle "genes". The ones that carry two are called homozygous and there are numerous health problems associated with this status (usually improper development of eyes, ears, heart, and brain). These dogs will look merle and (God forbid) if they are bred 100% of the pups will be merle.

 

Normal merles carry just one gene, which is expressed (you can see the merle) because it's dominant. If one of these is bred to a normal merle, then each pup has a 50% chance to inherit either the merle gene, or the "non-merle gene" which will produce a solid pup with no merle genetics. This is not quite the same as saying 50% of the pups will be merle. Any number of pups might be merle each time the cross is done.

 

It's important to understand this because diseases and health defects operate by the same principles of inheritance - and we will most likely be able to understand behavioral characterists similiarly also, someday. It's "more fun" to learn using color, however. :rolleyes:

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Originally posted by Rebecca, Brook Cove Farm:

Normal merles carry just one gene, which is expressed (you can see the merle) because it's dominant. If one of these is bred to a normal merle, then each pup has a 50% chance to inherit either the merle gene, or the "non-merle gene" which will produce a solid pup with no merle genetics. This is not quite the same as saying 50% of the pups will be merle. Any number of pups might be merle each time the cross is done.

Well - sort of, but if you were to (god forbid) purposely breed two "normal" merles together, you would really only stand a 25% chance of getting a solid, a 50% chance of getting a "normal merle" and a 25% chance of getting a homozygous merle(usually mostly white,and usually visually and/or hearing impaired). It's believed that some really defective "double merles" may die in-utero and never be born. As you said, it's only a statistical "chance" - the actual litter breakdown could vary. That is why "color breed" people don't do the merle-merle crosses (except with rare demented exception in the so-called name of dog fashion).
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Merle-merle crosses appear to be de rigeur for working Aussie people. If you go to the breeder websites (and there aren't many working Aussie breeders anymore so it won't take long) you'll see many merle-merle breedings described. Normally the litters reported seem suspiciously small. I suspect the homozygous merles get bucketed at birth and not counted.

 

I'm not sure why this is. It could be that there are so many merle Aussies, and so few working Aussies altogether, that the breeders feel there is no choice but to breed merles.

 

Breed ring Sheltie people, and Lassie Collie people, will sometimes purposely breed two merles in hopes of getting a healthy homozygous merle to use as a stud, since all of his get will be merle. I think I also remember hearing about one or two that were actually shown, but excessive white is frowned upon (not a DQ though) so I doubt they had much success.

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Originally posted by SoloRiver:

Merle-merle crosses appear to be de rigeur for working Aussie people. It could be that there are so many merle Aussies, and so few working Aussies altogether, that the breeders feel there is no choice but to breed merles...

Breed ring Sheltie people, and Lassie Collie people...

Haven't checked out the Aussie websites, but what kind of pretzel logic is that? I do know a woman with conformation shelties who bred one of those homozygous mostly white shelties years ago (I think "Ghost of a Chance" was his name)- she stood him at stud - just bizarro in my mind. Weird thing is, supposedly even a visually/hearing affected homozygous merle won't pass the defects along if bred to a solid color. But I wonder if other internal deformities (such as internal organ problems)that can be associated with the homozygous-ness can be propogated. I have my own suspicions. Guess I've seen too many "lethal white" paint horse foals to feel comfortable with anybody purposely "testing Mother Nature".
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The double merle does not pass the associated defects along to offspring if mated to a non-merle, but to me the point is that the double merle himself has to live with the defects. To deliberately produce a dog which is likely to be deaf and/or blind just so that you can breed that dog and be sure of getting 100% merle offspring (or to get more "crystalline" colors, which I have also heard) is sick, IMO.

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Don't know about web sites but I hang out with working aussie people a lot and they are all well aware of the merle/merle issues. The problem seems to stem from way far back when people started breeding "those little blue dogs" to work stock. Fast forward lots of years and you have a gene pool with lots of merle in it and breeding decisions become one of trying to keep the baby and the bath water. If your goal is to develop and preserve working dogs, you may have to compromise. Nobody I know breeds for color; they breed for work in spite of color, so I certainly would not say it's "de rigeur" but rather "par n?cessit?"

 

Kathy

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i'm getting a bit lost with all this as well!

would it mean that if a blue merle bitch has a litter that contained say 1 black and white, does that mean the sire had to be a 'non merle'?

i ask because when i was looking for another dog, before i got brighid, i went to see a litter from a merle bitch. all 7 pups were merle and there was something not quite right with them. i dont know what, but i knew i did NOT want one of those pups. (obviously i cant say the sire was a merle, i didnt see him).

it would be good to know that the presence of a different colour within a litter could guarantee that the breeding was not merle X merle.

i would just like to say that i wouldnt but a pup that i could not see the sire of, or that i would buy from a breeder who could not tell me the parentage. this is just for curiosities sake! tring to begin to understand all of this!

many thanks

love

donna

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Originally posted by donna frankland (uk):

i'm getting a bit lost with all this as well!

would it mean that if a blue merle bitch has a litter that contained say 1 black and white, does that mean the sire had to be a 'non merle'?

It means that sire of that particular puppy was not merle. (It's possible for there to be multiple sires for a litter.) It would be unusual but not impossible to have all merles born to a merle and a solid parent. If the breeder was less than reputable, I'd seriously question an all merle litter - especially if there was a lot of white with only patches of merle on the puppies. I also know of at least one merle bitch that produced and all solid color litter when bred to a solid dog, also unusual but quite possible.
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Originally posted by donna frankland (uk):

i'm getting a bit lost with all this as well!

would it mean that if a blue merle bitch has a litter that contained say 1 black and white, does that mean the sire had to be a 'non merle'?

No. Even when breeding 2 merles together, you have a 25% chance of getting pups that are non merle .

 

25% chance of homozygous merle (2 merle genes)

50% chance heterozygous merle (1 merle gene)

25% non merle. (no merle genes)

 

The about is of course assuming that neither parent is homozygous merle. If one parent IS homozygous, then you have no chance of a non merle.

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I know some folks who bred their black and white bitch to a merle stud. Yes, they were hoping to get the color (this was a sport breeding) and were disappointed when one one measly puppy came out merle.

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So if you breed a heterozygous red merle to a homozygous normal black dog you will get blue merle and black pups? The red would become a hidden recessive for both the merles and solids? However, if the normal dog is heterozygous black/red then the pups would be red merle, blue merle, black and red?

 

Olivia

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I actually have a friend who had the "all merle" litter actually happen. She has a working sheltie (no lie, she runs her little farm with him and he's actually pretty nice and I don't even feel the urge to qualify that with the usual "for a sheltie" though maybe we can all assume the qualification, "for a non-border collie" :rolleyes: ). He's blue merle and after many years she finally found a female that worked at a similiar level to her male. They produced ALL merles.

 

Now on top of the hassle she gets because her male is "bigger than standard" and her focus on working ability - she gets the people who look askance at all the merles she got. It doesn't matter that her male is obviously not homozygous - quite the opposite, he's sort of a muddy merle with very minimal white trim.

 

I did forget that two normal merles can produce solids and normal merles, duh. I was mentally jumping ahead to the next generation with the homzygous merles.

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Originally posted by Olivia:

So if you breed a heterozygous red merle to a homozygous normal black dog you will get blue merle and black pups? The red would become a hidden recessive for both the merles and solids? However, if the normal dog is heterozygous black/red then the pups would be red merle, blue merle, black and red?

 

Olivia

and, don't forget - if the sire and dam are tri's or tri-factored or dilute factored, you can also get tri's (both red and/or black and/or merle) and/or blue and or lilac!
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quote:Well - sort of, but if you were to (god forbid) purposely breed two "normal" merles together, you would really only stand a 25% chance of getting a solid, a 50% chance of getting a "normal merle" and a 25% chance of getting a homozygous merle(usually mostly white,and usually visually and/or hearing impaired). It's believed that some really defective "double merles" may die in-utero and never be born. As you said, it's only a statistical "chance" - the actual litter breakdown could vary. That is why "color breed" people don't do the merle-merle crosses (except with rare demented exception in the so-called name of dog fashion).

 

-------------------------

I find this very interesting as I once had a dog that was all white except a merle face. He was a rescue. He passed all physical exams and appeared to be quite healthy. At first we thought he was a double merle, but later figured he was a cross between a merle Aussie and a predominate white Border Collie. This made more sense as he appeared healthy. Regardless he had the brains of a Border with the tenacity of an Aussie. Interesting dog for sure. Unfortunately I had a TIA (minor stroke) and could no longer care for him.

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