The Recessive Yorkie
 

Below is a list, taken from Ann Seranne's The Joy of Breeding Your Own Show Dog. It is a list of traits generally agreed to be either dominate or recessive. With the Yorkshire Terrier having a high percentage of desirable traits being recessive, it's no wonder that this is an incredibly difficult breed to breed correct and pure.

Dominant .... Recessive
Long Head .... Short Head
Large or Long Ears .... Small or Short Ears
Low-set Ears .... High-set Ears
Wide Ear Leather .... Narrow Ear Leather
Coarse Skull .... Fine Skull
Short Foreface .... Long Foreface
Erect Ears .... Drop or Tipped ears
Dark Eyes .... Light Eyes
Normal Eyes .... Large Bulging Eyes in Some Breeds
Brown Eyes .... Blue Eyes
Wire Coat .... Smooth Coat
Short Coat .... Long Coat
Curly Coat .... Straight Coat
Poor Layback of Shoulder .... Good Layback of Shoulder
Poorly Angulated Stifle .... Well Angulated Stifle
High-set Tail .... Low-set Tail
Heavy Bone .... Light Bone
Deep Chest .... Shallow Chest
Straight Topline .... Swayback
Good Spring of Rib .... Poor Spring of Rib
Short Stifle .... Long Stifle
Light Pigment .... Dark Pigment on Skin of White Dogs
Normal Hearing .... Deafness
Good Eyesight ..... Night Blindness
Good Eye Pigment .... Walleyes
Self-color .... Parti-color
Black Nose .... Dudley Nose
Good Mouth .... Overshot or Undershot
Normal Palate ..... Cleft palate
Normal Lip .... Hare Lip
Straight tail .... Kinked or Bent Tail

It is noted that some are incompletely dominate, some are linked to others and others, such as cleft palate, are considered lethal genes.

Could we use this list as a basis to discuss breeding Yorkshires? Genotype vs phenotype, line-breeding, in-breeding, out-crossing, linked genes, etc. are all possible subjects for breeding healthy, typey Yorkshire terriers. I know many of these aspects have been previously discussed, but it might be nice to see them discussed in a cohesive manner with your own personal experiences.

Thanks in advance for your input.

I have this book...very interesting!

Dont you mean Yorkshire Terrier having a high percentage of desirable traits being dominant??

I think you mean the dominant traits are more desireable:confused:

No, I mean that many of the desirable traits, particularly those dealing with the ears and coat, are considered genetically recessive.

it's easir to breed for a recessive trait since breeding two recessive together will always breed true. For example if you breed two partis together you will only get partis.

Point taken, and I agree with you about the partis. My understanding is that it's the piebald gene that expresses the white color.

I don't think that logic is true for all recessive traits, however. Not all traits are governed by a single pair of genes. For example, I have a boy and girl, both with long silky coats. I have bred them twice and, with the first litter, all the pups had gorgeous, long, silky coats. With the second breeding, I got 3 pups with the long coats and one with a slightly wiry coat. Since the long, straight coat is the result of recessive genes, one would think that both parents would breed true if there was only one pair of genes controlling these factors.

There are a lot more traits on the list than just ears and coat though and most of THOSE are dominent so I would say overall, the overall quality of the yorkshire terrier is dominant.

This is easily explicable! Both of your yorkie parents are CARRIERS of dominant and recessive traits. This is called heterozygous. To be heterozygous means to have one dominent and one recessive allel given. Each allel is passed on by the parents of the pups. Therefore each pup can have a different geneotypic ratio which expresses different phenotypes. The different combinations for lets say a silky coated pup from two heterozygous parents can be SS (which is silky), Ss (which is silky), sS (which is silky), or ss (which is wirey). The reason for this is as long as a dominant trait (S) is given to the puppy the puppy will have a silky coat. If the puppy obtained both (s) then the puppys coat will be wirey.:)

My understanding from what I've read is that a dog that displays a trait known to be recessive had to have inherited this gene from both parents and would therefore be homozygous for that trait, for example, two partis producing only partis. So how could two dogs that both exhibit the trait of a recessive gene produce other than that trait unless that trait is governed by more than one pair of genes?

I will say that both the sire and dam I mentioned in an earlier post do have long silky coats but both exhibit a slight bit of waviness along the hindquarters. The pups from the first litter show no hint of waviness in their coats. I did keep a girl from that litter but have not bred her yet so am unsure of what to expect. My thought is that if I use a male with a fully straight coat that I would see the pups have straight coats.

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My breeding philosphy
 

As a show breeder who has produced at least one champion from every litter of yorkies I've produced (one litter of 4 produced 3 champions), I can tell you that kennel blindness will destroy your breeding program in a heartbeat. Here is my breeding philosophy:

1. Seek out knowledgeable individuals who will honestly critique your bitch and tell you what needs to be improved. This person needs to feel they can be brutally honest, and you need to be able to take the criticism gracefully.
2. Breed each litter as if it is the last litter your bitch may ever produce. Money wisely spent on a quality stud will be money saved on handler and show expenses. The fact that you own a male, even if it is a champion, does not mean you should use that dog on every bitch you own.
3. Breed to the stud dog that most closely resembles your ideal dog. Be extremely critical of that dog and be sure that the traits that dog possesses are the same as those you need to correct in your female. Do not breed to anything that has faults you cannot live with, as you are bringing those traits into your gene pool. It's wise to know what the stud's parents looked like as well. Ask for referrals and talk to those other breeders to understand what the stud produces. Ask about faults, genetic problems and most of all, ask about litter size and puppy mortality. Consistent litters of 1 or 2 puppies can be indicative of a problem which causes fetal death and the puppies to be reabsorbed.
4. Look at what the stud dog produces. Sometimes you are better off breeding to the father of that lovely dog you see in the ring if the mother did not possess those traits you admire in that dog. Remember, a "proven" stud dog doesn't simply mean the dog is fertile. It means that the stud transmits it's desireable traits to it's offspring on a consistent basis. If have the opportunity, learn about entire litters sired by that dog, including those that were sold as pets and why they didn't make the grade.
5. If you are breeding to show, find out how many champions that dog has produced. A huge stud fee doesn't necessarily equate to quality offspring. Keep in mind, not all specials are truly the best dogs in the country, but rather their owners have the resources to campaign the dog. You might find a really great stud dog owned by a small scale show breeder that will produce the results you want without a massive stud fee.

In my opinion, the reason people practice line breeding is because they do not have a comfort level with knowing what traits to expect from a dog. So they go the safe route and hope for the best. If you can be honest with yourself about what you would choose to improve your female and breed to a dog that produces those traits, you will have a great level of success.

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Thanks, Rosanne, for your comments. I can fully appreciate what you say about kennel blindness. I do try to keep a critical eye on my dogs' qualities and faults.

With my first breeding of the pair I mentioned, I was very pleased with the results. I kept all 3 pups until 9 months of age as I wanted to see them develop to know what I was producing. I also had a show breeder friend evaluate my pups, I placed two of them and kept a female. The male from the litter is in my avatar photo.

I have not got into showing yet. My exhibitor friend recently saw my female that I kept and thought she was show quality except for the fact that I had spoiled her and she doubted her attitude in the ring. I admit she is right for she was a wonderfully spunky girl that has become a ninny baby LOL. So I have to work on how I raise my pups to maintain that attitude necessary.

As for my pup's parents, I know the dam's lineage well as well as the sire on his paternal side. I don't know so much about the maternal side and feel that may well have been where my surprise pup came from in the second litter. I hope to breed my dam to my sire's father next time to hopefully give me more consistent quality.

I'm a little surprised by your comment that line breeding was going the safe route. I would think that line breeding would involve more consideration and that seeking an outside stud would be the easier thing. I'm not being critical...just a little surprised. More food for thought, I suppose.

Thanks again for the response. It is much appreciated.

I'm a little surprised by your comment that line breeding was going the safe route. I would think that line breeding would involve more consideration and that seeking an outside stud would be the easier thing. I'm not being critical...just a little surprised. More food for thought, I suppose.

Thanks again for the response. It is much appreciated.[/QUOTE]

When you line breed it is a safer route because you know the type of yorkie your producing...when you introduce an outcross your really not sure what you are getting when you bring in the outcross...did that make sense?

Donna Bird

Very interesting thread!
And along the same lines... I believe the gene that produces the "blue" in yorkies is the greying gene. Does anyone know how this works and whether it is dominate or recessive and how it expresses itself? I find this all so very interesting. Maybe it's because my husband and I both have browinsh hazel eyes yet both of our children have blue eyes.....

This is very interesting, I learned a lot! Now I know a bit more of what to say when people comment on how yorkies differ so much from one another. (in addition to poor breeding that is.)

Donna, that makes perfect sense when thinking of results. When I saw the word 'safer', I took it to mean safer concerning potential health problems. Assuming you were equally comfortable with the health background of either an outcross stud or one of your line, would you not have the added 'potential' risk of an unforseen health issue crop up with linebreeding that could become more likely the tighter the line?

I think rosemark was using 'safer' as you say and I was thinking about it in a whole 'nother way.

This is a subject I find fascinating yet some things just haven't gelled in my brain as I'd like them to. It's like I understand but don't quite *get* it as much as I'd like. I know some things only experience teaches but I love discussing things with those that have 'been there, done that'. It always leaves me with a better understanding of some facet of our Yorkies.

Also take into consideration when you bring in an outcross whether or not you are comfortable with the "potential" risk of a health issue you have to realize take Liver Shunt for example...you are taking a risk when bringing in an outcross not knowing if those two won't produce Liver Shunt even tho either line has produced it it can throw one because of a recessive gene you didn't know about even tho both parents have good BAT's. Some breedings just don't go well together. When outcrossing you are taking a risk. It is safer to line breed because mostly you know what's been thrown, type you like and if you've had no health issues it is considerably safer to line breed.
That is why we always say know your lines, know your health issues ect.
I don't mind an outcross when you've backed yourself into a corner as far as line breeding but you take the risk of bringing the undesirable traits when you outcross but can keep in mind you can bring in what you might be lacking in your own breeding. So it is actually safer to line breed than outcross :)

Donna Bird

Here is another interesting link on genetics. Some of you may have already seen this:
Relation

I've read that information before....there are quite a few software programs out there that will figure it for you. Here's an on line source you can try...

Inbreeding calculator

I'm still reading Genetics of the Dog plus reading on line....here's a fairly easy to understand explaination.

Do You Feel Lucky? - Genetics for Breeders, Part 1

Thanks for the links, y'all. I had seen most of the info before, but not from those exact links. I had never heard of kinship and relationship coefficients before, though.

I often see where the dangers of inbreeding are mentioned, but really, linebreeding and inbreeding so similar, differing mainly by degrees. Linebreeding is far more generally accepted but it seems that inbreeding is used very often in developing new breeds. Once developed, linebreeding seems to be the preferred tool used to maintain type while providing for genetic diversity. Would that be a fair statement?

I have read that Huddersfield Ben was the product of several successive generations of mother-son breedings so the very early Yorkies were highly inbred.

One notable group of dogs I've read about that are inbred is the seeing eye dogs. I have read that the average breeding coefficient is .25 among the ones bred in Morristown, NJ and that they are among the healthiest group of dogs anywhere. Theirs is a unique circumstance, however. Beyond rigorous health testing, those breeders keep their pups far longer than the average breeder and also have the advantage of closely following each pup throughout its lifetime so I'm sure they absolutely know their lines, regarding both health and temperament.

Donna, thanks for your explanation of line-breeding vs out-crossing. I'm at a point where I'm thinking about how to proceed with what I have. I have a very good quality bitch that I have bred to my stud and have had good, but inconsistent results. I think going back to my bitch's breeder for a stud might be the way I need to move forward. She has some wonderful dogs but isn't so much the 'mentor' type so I need to work on a better relationship with her so I may, hopefully, build for the future.

Here's a link to some interesting info I found...

Line Breeding

:thumbup: awesome thread!!! I love talkin genetics, but for some reason I cannot retain it and ALWAYS have to break out the biology books for reference :) and take great notes. This thread is a keeper in my favorites.

Thanks a bunch for posting on this topic.

I've heard that breeding Yorkies is part science, part art, and part luck. The science part alone is daunting for me, but some of it is starting to gel.

Below is something I copied and pasted from the link I posted. I find it interesting because I had never seen the importance of the dam emphasized so.


In all mammals the females are "X" "X" and males are "X" "Y" which means that only females carry the genetic code particular to the part of the gene string that is missing in all males. Horse Breeders refer to it the "X Factor" and have demonstrated that the gene responsible for the large heart so many great racing stallions have can be traced back thru their motherlines to a single mare that lived more than 100 years ago. If a stallion has an oversized heart - like Secretariat - this particular mare will show up in his motherlines over and over again. The mares themselves don't have the large heart but they carry the gene for it on their “X” chromosome. Like wise the stallions do not throw the large heart themselves.

And so it is with German Shorthairs. The bitches are far more important than the studs in carrying particular genes forward. Understand that this is true even if the genes most sought were originally found in a pre-potent male. The key for any successful Breeder is to isolate those females that carried his traits and breed off of them. It has been our experience that many important traits are indeed sex linked and carried by the dames from generation to generation.

Successful Breeders realize they are fighting "the drag of the breed," which is the tendency for all animals to breed back toward mediocrity. If it didn't work this way super species and super races would have developed long ago in every animal on earth. For instance in human beings it is impossible to breed parents with high IQs together to produce higher IQs. Even when two genius have children the average IQ of their children will be half way between normal and the average of their IQs.

It's not about Yorkies specifically, but it does make me think of things in a different way. I had read before of Huddersfield Ben being the product of several generations of mother/son breedings. The info I posted above helps put into perspective, for me, why it was mother/son rather than father/daughter breedings.