mheath0429 wrote:

I feel lame - my dogs both have two of the same colored eyes. boring.

Not such a bad thing - a lot of the show dog bloodlines typically only have the brown eyes. Blue eyes isn't a fault, but was unfavored for quite awhile, and even today tends to be avoided in the show dog as it does not show the desired eye shape as well. But I bet you knew that all already didn't you .

so i think what you are trying to get at is
mono or homochromia for both eyes being the same
heterochromia is for each eye being different
and sectoral heterchromia is for eyes being partly colored.

but all of the things listed above, homo, hetero, and sectoral are all found in humans. there are many (i think like over 15 genes?) that are associated with eye color in humans, and specific mutations in different genes play a role in the degree of pigmentation in the eyes. its a really complex system.

heterochromia doesn't have to do with the pigment of each eye being under control of their own specific genes. the genes for both, or all parts of the eye are the same (you have the same DNA in everysingle one of your sells aside from anything that has undergone a denovo mutation since you were concieved). its a matter of "gene silencing" (gene imprinting). Basically, you don't really need two copies of each gene. So what happens, is the body has a bunch of enzymes that can silence certain genes by putting a chemical group (methyl) on particular genes, which stops translation. this pattern of DNA methylation changes throughout development, so you can have different cells that have different patterns of gene expression. with something like eye color it is really noticeable because eye pigmentation is so easily varied by one or two mutations and is under control of a number of genes. Another really cool example of this is the calico cat. Calico's can only be females (well, unless they have trisomy of the x gene, but thats really rare). the reason they have "splotches" of different colors is because of these idea of imprinting. for cats, coat color is found on the X-chromosome. Since females have two X-chromosomes, the chromosome that chooses to be expressed varies, and depending on which chromosome is active dictates the color of the cat.

i have never studied dog genetics - let alone dog eye genetics, so i can't say for sure that my response is correct (since earlier posts differ significantly from mine). but i do know that it is the case for human eyes, and the calico example. my guess is it is the most plausible.

So Randy how would you relate that to Huskies having bi-eyed/particular-eyed manifestations?

Your info is interesting. What I was confused about originally, but cleared up by Lani, was that in humans the default or standard (normal) is monochromia/homochromia and therefore any variations are genetic defects. But for Huskies, apparently the default is not mono/homochromia, I guess in fact there can be no default to speak of because bi-eyed and parti-eyed and dual-eyed are all perfectly normal in a genetic sense. I presume this is why variations in eye color are acceptable as the breed standard as opposed to selecting for a defect subsequently being adopted by the breed standard.

I'm glad I started this thread

That said, anybody know what the rate of prevalence is for eye variations in the breed?

LoveMyBrat wrote:

so i think what you are trying to get at is
mono or homochromia for both eyes being the same
heterochromia is for each eye being different
and sectoral heterchromia is for eyes being partly colored.

but all of the things listed above, homo, hetero, and sectoral are all found in humans. there are many (i think like over 15 genes?) that are associated with eye color in humans, and specific mutations in different genes play a role in the degree of pigmentation in the eyes. its a really complex system.

heterochromia doesn't have to do with the pigment of each eye being under control of their own specific genes. the genes for both, or all parts of the eye are the same (you have the same DNA in everysingle one of your sells aside from anything that has undergone a denovo mutation since you were concieved). its a matter of "gene silencing" (gene imprinting). Basically, you don't really need two copies of each gene. So what happens, is the body has a bunch of enzymes that can silence certain genes by putting a chemical group (methyl) on particular genes, which stops translation. this pattern of DNA methylation changes throughout development, so you can have different cells that have different patterns of gene expression. with something like eye color it is really noticeable because eye pigmentation is so easily varied by one or two mutations and is under control of a number of genes. Another really cool example of this is the calico cat. Calico's can only be females (well, unless they have trisomy of the x gene, but thats really rare). the reason they have "splotches" of different colors is because of these idea of imprinting. for cats, coat color is found on the X-chromosome. Since females have two X-chromosomes, the chromosome that chooses to be expressed varies, and depending on which chromosome is active dictates the color of the cat.

i have never studied dog genetics - let alone dog eye genetics, so i can't say for sure that my response is correct (since earlier posts differ significantly from mine). but i do know that it is the case for human eyes, and the calico example. my guess is it is the most plausible.

Very nicely put, and correct - but as was pointed out above inheritance in Siberians is different than it is humans. While these traits appear in humans, they appear as the result of some type of mutation or abnormal variation in the normal pattern - eye color is determined concurrently in both eyes, minus the variations you mentioned. In Siberians (and a few other breeds - possibly in all dogs - can't say for certain as I only looked into Siberians), the eye color is not a result of a mutation or abnormal variation. Color of each eye is determined independently by a different group of genes. Hence why the various eye colors are not considered to be a fault.

seattlesibe wrote:

So Randy how would you relate that to Huskies having bi-eyed/particular-eyed manifestations?

Your info is interesting. What I was confused about originally, but cleared up by Lani, was that in humans the default or standard (normal) is monochromia/homochromia and therefore any variations are genetic defects. But for Huskies, apparently the default is not mono/homochromia, I guess in fact there can be no default to speak of because bi-eyed and parti-eyed and dual-eyed are all perfectly normal in a genetic sense. I presume this is why variations in eye color are acceptable as the breed standard as opposed to selecting for a defect subsequently being adopted by the breed standard.

I'm glad I started this thread

Jeff to really find the answer to your question, you have to dig back into the history of the breed itself. Siberian huskies are actually one of the relative late comers to the world of recognized dog breeds. You also have to go beyond just looking in the popular books on Siberian huskies. If you look back to Lenard Seppala and some of the early pictures of his dogs that are now online and do the same with Harry Wheeler, you begin to understand just how much this "breed" has changed from the original Churchi dogs that were brought over, and yet how similar it also remains. In some ways, while it is just as biased as it claims the other side is, if you look into the history of the Seppala sled dog, you get a better sense of the breeds origin than you will if you look in the popular books. Since its foundation as a "breed" the Siberian has really gone in three different directions; Today's popular idealized show/sled dog (which is what the breed standard is based on), the working sled dogs which are often considered to be outside the breed standard, and the Seppala sled dogs. While true Seppala enthusiasts will argue that their breed is a seperate breed from the Siberian, the two have the exact same origins - the dogs originally brought over from Russia/Siberia and given into the care/training of Lenard Seppala. Seppala later transfered ownership of his remaining stock into the care of Harry Wheeler, who continued to use the kennel name "of Seppala". All of this of course was before the breed became a registered breed. If you dig deep enough, you can actually find information on one of the earliest Siberian kennels in Alaska that was known for its pure white dogs, and yet for many years, pure white was not considered to be a "standard" coat color in Siberians (just as a side note - the story behind the red and whites is interesting as well). The big schism/split occurred as a result of the separation between the show Siberian (around which the standard was based) and the working sled dog, whose owners were focused far more on the working class traits and speed then they were on a show standard. The breed standard calls for an almond shaped eye. While blue was never truly considered to be a fault, many judges and breeders did not like it because it didn't show the required almond-shape as well as the brown, and so breeders looking to establish show lines early on, selected against it. Those with working sled dogs never did. All of that of course is a bit of an over simplification, but you get the general idea. This is why a reputable breeder will tell you that if you have a kennel or breeder that is producing pups with lots of or primarily blue eyes, they are not breeding for quality, they are focusing on obvious traits like coat or eye color instead.

Since the trait existed in the earliest of the working class dogs, it could hardly be considered to be a fault, and so has always been included within the standard. For many years however, it was a unfavored trait among the show breeders. So the answer to your prevalence question is really not an easy one to answer. Many Siberians out there have the trait, but it is significantly less prevalent in the show dogs than in it is in the working sled dog and pet population.

Wow, thank you Randy for the historical info. That was really helpful.

You really bring attention to the issue of breed standard and it's purpose or functionality. With my interest in the prevalence of eye distribution patterns, I see this also coming into play.

In simplistic terms, if there were 100 Huskies total, how many would be dual-blue eyed, bi-eyed, parti-eyed , and dual-brown (other not-blues)......and subsequently, how many of those 100 would be in standard? I know it's tough to say for sure but anbody who wants to estimate it would be interesting to think about.

So when do you suppose the origin of bi/parti -eyed took effect? It is rather unusual for eye color to be genetically separate from eye to eye in a mammal.

Jeff those numbers are pretty impossible to even begin to guestimate.

In regards to the trait showing up, I would guess those traits were present in the dogs that were brought over from Siberian, but as for how long they existed in the breed over there, it is hard to say. Wolves can have brown or blue eyes, but they do not express the bi/parti- effect as Siberians do. So it would have had to have appeared sometime in between, but that is still a very long chunk of time.

Yeah, I figured Randy. Well thanks for all your info. You're quite the breed historian!

I've just had a lot of years to learn about them and history happens to be something I enjoy. I like digging into things like that. Kind of like pedigrees, I love to follow lines on pedigrees back to see how far back you can take them. There is a pretty cool online site you can use that will sometimes take you all the way back to the foundation of the breed.

What site?

The site is http://pawvillage.com/. You go in and select your breed, and then you start entering different individuals on your dogs pedigree until you find one that is entered in the data set of the site, then you can begin tracing it back by clicking on its pedigree and selecting of its forebearers and so on and so forth. Many of the entries have pictures as well, so you can click on those and see what your puppies forebearers looked like as well. In some cases you can trace all the way back to Seppala. Be careful though, you can litterly lose yourself for hours at a time in this thing .

Sweet, thanks!