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 Post Posted: Wed May 13, 2009 1:07 pm 
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The oldest breed standards we have denote Lacys should not have extensive white spotting. That has been defined as white being allowed only on the chest, stomach and paws. White on the face is a major fault that is supposed to disqualify dogs from being registered or bred. This goes back to the desire to prevent out crossing and keep the health issues of spotted curs like Catahoulas out of the Lacy breed.

White markings are controlled at the S locus. S is a solid colored dog, which can express small white markings on their chest, toes and tip of the tail due to incomplete melnocyte distribution during embryogenesis (http://homepage.usask.ca/~schmutz/pathway.html). si creates Irish spotting, which is confined to the neck, chest, belly, lower legs and tip of the tail. White marking can be negatively modified to slightly reduce these markings. Just as with other coat color genes, each dogs have two S genes, which they inherit from their parents' set of S genes, and so on. It appears a properly marked Lacy is SS, Ssi or modified sisi.

Sadie shows the typically small white markings of SS, http://www.flickr.com/photos/julieanna/3436313241/. A dog like Patch, with his namesake chest marking and white feet http://www.flickr.com/photos/julieanna/ ... 027566732/, is a properly modified sisi. He has produced Ssi offspring, http://www.flickr.com/photos/julieanna/ ... 027566732/, which have more significant markings than SS but not the large patch of a modified sisi.

From studies done on collies and other solid headed dogs, scientists believe white markings on the head are controlled by a different modifier or even a separate gene. Even though researchers have yet to document every variation of the spotting gene, breeding away from white markings on the head a simple task for any responsible breeders No, it is not inevitable that white faces will show up in litters, just as it is not inevitable that a black-mouthed dog will show up in a litter. If the gene or modifier isn't there, you won't have the fault, and if you pick the right dogs to breed, the gene or modifier won't be there.

You can easily trace white markings on the head by researching your dog's ancestors, siblings and progeny. If you see any white faces within two generations, do not breed that dog. For example, if the dog comes from a litter in which other puppies had white faces, even the solid siblings should not be bred because they likely have the genes to pass on those markings. In a recent litter we've seen pictures of on another Lacy site, it is obvious the excessive white markings came from the stud, who himself has a white stripe down his face. This stud has produced solid colored progeny in the past, yet those properly marked dogs went on to produce their own offspring with excessive white markings, http://i26.photobucket.com/albums/c124/ ... 1242234751. So it isn't just the parents that make a difference, the grandparents and siblings offer important insight into whether or a not a dog should be bred.

If you are interested in further reading, I found this study on Border Collie markings very interesting, http://genomebiology.com/2000/1/2/research/0004/. There is some additional information about white markings and how breeders have selected for them on this Brittany site, http://www.wyngold-brittanys.com/BrittanyColor.html. And I've posted these before for coat color, but these two sites always have nice notes and links to further research on spotting genes, http://homepage.usask.ca/~schmutz/dogspots.html and http://bowlingsite.mcf.com/GENETICS/ColorGen.html.

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"You must be a very small minority no matter who you hang around with. Maybe you should start a magazine, Vegetarian Hog Dogging Monthly, find some like-minded individuals."
- Inspiration for my next project from TBH

True Blue Lacys: http://www.truebluelacys.com
More Lacy Pics: http://www.flickr.com/photos/julieanna/sets/72157605027566732/


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 Post Posted: Wed May 13, 2009 1:59 pm 
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When you say Irish spotting, are you talking about this?

Image

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 Post Posted: Wed May 13, 2009 2:55 pm 
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Yes, the large white markings on Aggie means she's most likely a modified sisi, maybe an Ssi. The extended white markings on the chest and the white paws are typical of Irish spotting.

But Irish spotting is the white markings, not the speckles, if that's what you are asking about. I know the names are sort of confusing.

Those speckles are called ticking. It is controlled by a separate gene at the T locus. Ticking is a dominant gene, so dogs with TT or Tt will express ticking, while a dog must be tt to have no ticking. The degree and density of ticking can vary, which is likely controlled at the T locus, not the S locus. But you do need to have at least one white spotting gene, which would be si for Lacys, to see it. For example, an SS dog could be TT, but you won't see any ticking because they don't have any s markings to express it on. But ticking isn't in every line of Lacys, and from what I've seen, it's pretty easy to track.

Ticking is most common in bird dogs (ex: GS/WPs and Setters) and it's also the gene responsible for spots on Dalmations. The gene is distinctly different from the ones that cause merle (ex: Catahoulas and Australian Shepherds) and brindle (ex: Plotts) patterns.

_________________
"You must be a very small minority no matter who you hang around with. Maybe you should start a magazine, Vegetarian Hog Dogging Monthly, find some like-minded individuals."
- Inspiration for my next project from TBH

True Blue Lacys: http://www.truebluelacys.com
More Lacy Pics: http://www.flickr.com/photos/julieanna/sets/72157605027566732/


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 Post Posted: Wed May 13, 2009 3:11 pm 
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Quote:
Those speckles are called ticking.


#-o Oops, I knew that!

Thanks for working on this, Julie!

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