Could someone clarify about double merle?

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Lysette85

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I thought a double merle was the breeding of a merle dam and sire-(both of which only had 1 Merle parent) but I read somewhere else that an all white sheltie someone rescued was the result of 2 double Merles breeding. So...the puppies have mother and father merles and all 4 grandparents are merles. Could someone touch on this further?

Also-what causes color headed white (and what does that mean exactly)? Just that the dominant color is white? Is it just having more of the paling gene in a Merle parent?
 
Double merles are created by breeding two shelties with the merle gene, not just from breeding two double merles together. Since double merles have that merling gene, breeding two together would also produce double merles.

Color headed whites are different all together. Color headed whites occur when two white factored shelties are bred together. White factored shelties carry a gene that produces a white collar that goes all the way around their neck, white front legs and a while strip that goes down their belly from the front to back of the dog. These dogs don't have the genetic problems that double merles have.

Here is a photo of Sadie, who is likely white factored, because of her coloring. But she's spayed, so I'll never know (since we'll never see what her pups look like).

https://picasaweb.google.com/100567...hkey=Gv1sRgCMH7k7TPx7uTTA#5428484203213614530

I'm sure someone can pipe in with an explanation of the genetics, but that about sums it up. :smile2:
 
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I know that if two white factored dogs are bred, theres a 1/4 chance of there being a CHW puppy. I think both Missy's parents were white factored because out of the litter of 4, there was 1 CHW. Now the question is... if both of her parents were white factored, does that mean Missy is white factored too?
 
Jess041 said:
if both of her parents were white factored, does that mean Missy is white factored too?
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Not necessarily. There is a 1/4 chance she inherited two "non-white factored" genes from her parents, a 2/4 chance she got one white-factored gene from one parent, and none from the other, and a 1/4 chance of inheriting the white factoring from both. Had she done that, she would be white with a colored head.

I think to worry about white factoring in a breeding program is silly, but breeders place perfectly nice pets because they are white factored. I don't get it.
 
Lysette85 said:
I thought a double merle was the breeding of a merle dam and sire-(both of which only had 1 Merle parent) but I read somewhere else that an all white sheltie someone rescued was the result of 2 double Merles breeding. So...the puppies have mother and father merles and all 4 grandparents are merles. Could someone touch on this further?
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To my understanding a double merle is dog who inherited two merle genes, one from each parent. If you breed two dogs with one merle gene each (blue merle, sable merle, bi blue) then the puppies will have a 1/4 chance of being double merle, 1/4 of no merle gene and 1/2 and chance of one merle gene.

If you breed two double merle dogs together, every puppy in that litter will also be a double merle. It doesn't necessary mean the grandparents are double merles. They could've been a merle to merle breeding that produced double merle puppies.
 
ClantyreSheltie said:
Not necessarily. There is a 1/4 chance she inherited two "non-white factored" genes from her parents, a 2/4 chance she got one white-factored gene from one parent, and none from the other, and a 1/4 chance of inheriting the white factoring from both. Had she done that, she would be white with a colored head.

I think to worry about white factoring in a breeding program is silly, but breeders place perfectly nice pets because they are white factored. I don't get it.
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I was just curious, not planning on breeding or anything. Clearly Missy's breeder was not concerned about it either because she bred two white factored dogs!
 
The other thing is that you don't necessarily know what dogs are white factored. The theory is if they have white up the stifles, they are. I have two dogs with white up one stifle, and they didn't produce CHWs when bred. I also know ROM dog who they assumed was non-white factored, and then had a litter of three or four CHWs.
 
Jess041 said:
I was just curious, not planning on breeding or anything. Clearly Missy's breeder was not concerned about it either because she bred two white factored dogs!
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There is nothing wrong with breeding 2 white factored dogs togather, now breeding 2 merles togather that is a different story. CHW's are completely healthy and do not have the problems double merles do.
 
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