The History of Blue Merle in Shelties

Any dog with a merle parent can theoretically produce merle.

Remember that merle is not binary. It's not either there or not. Merle is a sliding scale, with expression being variable based on where the dog falls on that scale.

For argument, say that a dog with 0-40 repeats appears "solid", 41-70 appears "merle", and 70-100 appears "double merle". A dog with 35 repeats will appear solid, but can certainly pass those 35 repeats on to their get. So when bred to a "merle" with 55 repeats, that "solid" dog can produce a white dog. We know of this happening in solid to merle breedings. We also know of solid to double merle breedings that should have resulted in 100% merle dogs that produced solid dogs, who produced as solid dogs.

So yes, one parent has to carry some merle genetic material, even if it is not expressed. If you look at the pedigree of those two dogs, one of the four grandparents (though I would guess two) are merles.

Dogs are registered on phenotype (what they look like), not genotype (what they are). So unless there is a distinguishable merle spot on a cryptic, odds are they are registered as solid.
 
danisgoat said:
That is interesting. Is this the only breed of dog where this happens?
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As far as I know. They have a harlequin gene that masks it. So all harlequins are merles, but not all merles are harlequins. They sell the merle/not harlequins to pet homes on spay/neuter contracts. Double harlequins die in utero.
 
ClantyreSheltie said:
Any dog with a merle parent can theoretically produce merle.

Remember that merle is not binary. It's not either there or not. Merle is a sliding scale, with expression being variable based on where the dog falls on that scale.

For argument, say that a dog with 0-40 repeats appears "solid", 41-70 appears "merle", and 70-100 appears "double merle". A dog with 35 repeats will appear solid, but can certainly pass those 35 repeats on to their get. So when bred to a "merle" with 55 repeats, that "solid" dog can produce a white dog. We know of this happening in solid to merle breedings. We also know of solid to double merle breedings that should have resulted in 100% merle dogs that produced solid dogs, who produced as solid dogs.

So yes, one parent has to carry some merle genetic material, even if it is not expressed. If you look at the pedigree of those two dogs, one of the four grandparents (though I would guess two) are merles.

Dogs are registered on phenotype (what they look like), not genotype (what they are). So unless there is a distinguishable merle spot on a cryptic, odds are they are registered as solid.
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Very interesting....thanks so much.

I find it interesting that registries don't include genotypes in the registrations. This is definitely something that should be done.

I will try and explain this in simpler terms to my daughter and have her stress that this is why it is important that you do NOT breed a dog that you do not know the background of, because there could be a cryptic merle gene in there.

Thanks for all of your help, Rachael.
 
danisgoat said:
I find it interesting that registries don't include genotypes in the registrations. This is definitely something that should be done.
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They can't. A dog without a merled hair looks like a black dog. How would you know? The merle test was invalidated as far as I know.

Poodle people routinely register blue dogs as black, either because the dog is going to be shown dyed as a black, or because they honestly can't tell as puppies. Sometimes they correct the registration once the color changes as adults, sometimes not. Blue puppies are born just one shade below black, then they lighten up as they get older. It can be hard to tell what color they are, especially in the absence of black littermates to compare to. I bet there are some silver dogs registered as blue as well for the same reason. They are born dark and lighten the first few years.
 
Ok here is my question does it ever get "diluted" out of the gene pool, basically heres the "what if"...say you have a sable merle, breed that to say either a sable or tri, so there is no merle question. You end up with a sable merle puppy.
Than you again breed that sable merle puppy to either a sable or Tri, what are you chances of getting a sable merle? Does it decrease on out since in my theory of thinking you are mixing more and more non merle genes does it just dilute it out of the gene pool or is it just the same chance as breeding say a sable to a merle?

Sorry if it doest make sense hope someone can make sense of my question!:smile2:
 
Lightplum said:
Ok here is my question does it ever get "diluted" out of the gene pool, basically heres the "what if"...say you have a sable merle, breed that to say either a sable or tri, so there is no merle question. You end up with a sable merle puppy.
Than you again breed that sable merle puppy to either a sable or Tri, what are you chances of getting a sable merle? Does it decrease on out since in my theory of thinking you are mixing more and more non merle genes does it just dilute it out of the gene pool or is it just the same chance as breeding say a sable to a merle?

Sorry if it doest make sense hope someone can make sense of my question!:smile2:
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This is a great question!

I was wondering this as well. I am guessing it must....because if it didn't then it would be easy to list merle on the papers, because the gene would always be present.

Hmmmm........anyone know?
 
The presentation is this evening!

Wish them luck, please. Dandie just got her bath and I am going to blow dry her in a couple minutes so she can be a beautiful prop :lol:
 
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