Really interesting subject brought about by the ousting of yet another bad breeder. I still cannot get over that she bragged about breeding merle to merle since even though I don't know much about genetics I do know how to use google. :)

Although the article is over my head at times I found this & many others just by doing a google search of some of the terms used in recent comments above.
Analysis of Genetic Variation in 28 Dog Breed Populations With 100 Microsatellite Markers

I am grateful to see people really giving this some thought and how this may not be bad news but instead more information to help in breeding.
I don't believe we will ever find a perfect breeding world so my interest in sharing this information was intended for those that want to know more to improve the breed.

My initial impression upon hearing about the Yorkie's amount of variant genetic material explained why we see so many different physical traits this breed. I left the conversation with the thought that some variant genetic material was good because we do not want to breed for the "perfect" dog. That would be just as bad. The objective is to find the right amount of variant genetic material.

Hi, this is a relative early (2002) study based on only 100 genetic markers and only 28 breeds (including Yorkshire Terriers), so I would call these results preliminary. The data described by tricia208 are probably more recent and complete. Based on these 100 markers, the Bull Terrier had the least genetic variation, although Boxers and Miniature Bull Terriers were not far behind. The breeds with the most genetic variation were Jack Russell Terrier, followed by Pomeranian, Papillon, and Australian Shepherd. Yorkies were not far behind. They only examined between 40 and 50 dogs of each breed. I'm sure the more recent study is much more extensive, so we'll see. There are more gems buried in that study, but I'll wait until I've had a chance to see the more recent data before covering some of the finer points. Thanks for whetting our appetites!

I could read this stuff all day. Phil reads faster because he does not have to look up every 3rd word in a genetics dictionary! My simple mind agrees with his conclusions and I am pleased that the Yorkie and Boxer are at the high and low ends of the variant genetic material respectively. That leads me to believe (but not know) that with more current and complete information what I was told could be the case.

Although this is a 2002 study there is still a lot of valuable basic genetic information for those that wish to read it. Thanks for sharing this with the group. This is another good read by Elaine A. Ostrander Ph.D. for those that may be interested in basic canine genetics.
Both Ends of the Leash — The Human Links to Good Dogs with Bad Genes


http://www.nejm.org/doi/full/10.1056/NEJMra1204453

Happy reading!

Breeding to the standard is always the goal. But how to do that responsibly is the question.

But what if the standard is set in such a way, that it actually breeds in, dogs with health problems at least structurally. I hesitate to mention this, but the BBC special "Pedigree Dogs exposed" published what 4yrs or so ago, albeitly terribly biased did raise some very important issues with the health and the breeding practices and standards for some breeds.
It got so much press and exposure, that The Kennel Club, undertook a review of all Breed standards, and did "issue" changes to the standards for some breeds. Which is almost un-heard of for a registry to do; as it has always rested with the National Clubs to change breed standards.

Overall you do need gene diversity, that does produce dogs with-in the standard. For otherwise the gene pool narrows, and you find yourself (breeding wise) in a cul-de-sac.

I believe here in North America, although this is a very very unpopular view, with little support; that all Championships earned prior to two years old are provisional, and only finally granted after all health tests that can be done are done, and posted on the applicable health databases.

In the beginning as long as you do and post the health results, then good breeders can scruntinize them, along with the pedigree information, and can make much better informed decisions.

Eventually, when we get more and more genetic tests available to us as breeders, the health screenings for many breeds will become a moot point, if only clear to clear is bred. But there is more than just health screenings, there is temperament, attitude, coat, drive, and a whole host of breeding decisions that likely won't be able to be fixed on a particular genetic marker or two.

These threads are so very informative!

HA! :)

Some of the other interesting information in the 2002 paper is related to how geneticially variable the breeds are based on how old the breeds are, and how many dogs there are of a particular breed. The older the breed, the less variation you would expect, and the more dogs of a particular breed, the more variation you would expect. There was a slight tendency for this to be true, but it wasn't a strong trend.

I'll have to take a look at the Ostrander paper...

Excellent post. But I was just asking along the lines of the new member's original question on this subject - about breeders' responsibility to possibly breeding closer to the Yorkshire Terrier standard which seems to not have inherent unhealthy structural functions incorporated into it, unlike the Bulldog, Peke, Dachshund, for instance and how the possible large variant genetic material could be understood better and possibly help breed out other inherited problems in this breed one day, such as CT, liver shunt, LP, etc, which is all I was asking about at this point and not all of the other issues involved in pairing two dogs. And I think you answered that question at the end of your post which gives a certain kind of health hope.

I believe UKC also reviewed the breed standards for health, performance and agility and not just for conformation and appearance. They announced to all the parent clubs to fix the breed standards or UKC would correct them. I heard some rumbling for a while but it seems to have been accepted by all the parent clubs.

I agree that a breeder's goal should not be the 'perfect dog' and diversity is important to the health of a breed. I also agree that genetics will eventually address most health and physical problems within a breed. Testing will be available for all these dreaded conditions but we are probably a decade or so away from that even though genetics is advancing at a fast rate. The testing will also not be without error; it will be better but not perfect.

Interesting I thought the UKC did review the standards, how-ever the standards do not speak to health performance or agility. I did not review all current standards but the two breeds that I have.

Perhaps you can post the link to a breed standard at UKC that includes health performance and agility with-in the standard.

I agree that one should always breed to better the breed, and while our goal is the "perfect" dog it is a long ways off for any breed.

This is the link to UKC's News Release regarding breed standards and the effect on the health, function and performance of the dog. I know UKC was concerned about several breeds but I would prefer not posting that information. The Yorkie was not of concern to my knowledge. It is my understanding that all parent clubs have complied or working toward compliance with this new policy.

United Kennel Club: United Kennel Club, Inc. Announces Major Revisions To Its Breed Standards

I did not mean to get too far off the OP original subject or hijack the thread but the UKC policy is good news for all breeds and keeps the parent clubs thinking of all aspects of the breed. Thanks for asking.

Those "b," "sp," and "e" color mutants were bred in from other breeds :(

Coat color DNA testing in dogs: Theory meets practice

This article is behind a pay firewall, but it describes commercial DNA testing for coat color genes in dogs and has a table of alleles that have been tested for in various breeds, including the Yorkshire Terrier. Yorkies have been tested for the presence of "sp" (Parti color), "b" (brown), and "e" ("Gold Dust") alleles. The only problem is that these alleles have very specific DNA fingerprints, and they arose in other breeds. They could not have arisen spontaneously in the Yorkshire Terrier.

I am not to literate when it comes to all this so excuse me if this is a dumb question, but are you saying then that parties, chocolates and golden yorkies are not purebred? I only have traditional's but am just curious.

This is all too interesting, very informative.