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Genetics and the popular sire

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I found this article easy to understand but not the iPad I'm using so best I could do is cut and paste the article.

Here ya go

 

 

 

by Carol Beuchat PhD

 

The most common admonition of the geneticist to the dog breeder is to "avoid the Popular Sire Syndrome". At the same time, the most common advice from breeder to breeder is "breed the best to best". So the conundrum is obvious and the consequence predictable - the "best" dogs are the most sought after, so they sire the most offspring and become popular sires.

 

The Popularity of Popular Sires

Even a century ago Williams Haynes (1915) was writing about the "Effect of the popular sire", noting that in three terrier breeds that he examined - Irish Terriers, Scottish Terriers, and Fox Terriers - about 40% of the puppies were sired by only 20% of the sires. Back then, "popularity" was quite different than now - his "prolific" dogs sired 5-7 litters, which would be completely unremarkable today. And surprisingly, Haynes thought that popular sires actually benefitted the breed by contributing to the preservation of variability in type.

 

Superficially it might appear that if approximately 40% of the puppies each year are sired by but 20% of the stud dogs this would eventually result in the greatest uniformity of type. The selected sires are all to a greater or lesser degree exceptional animals, but they are not selected by any uniform system. Most of them excel in some particular physical point, but they do not excel in the same points or in the same degree, nor even, in some cases, in the same direction. Here the personal equation, the ideals of different breeders, is at work, and the result is that since a few males not themselves of uniform type sire a greater-than-average number of offspring they disturb the race average of the following generation and introduce abnormal amounts of variation. The fact therefore, that artificial selection gives to certain selected, but not uniform, males an undue preponderance of influence must always keep the type of domestic animals in an unstable state. This seems to me an important factor in the great variability always noted among domesticated breeds.

 

Haynes thought popular sires were a good thing, because he thought they were sufficiently different from each other that they prevented the breed from becoming too "uniform". How then did the popular sire go from contributing to the quality of the gene pool in 1915, to the source of a problem to be avoided by breeders 100 years later? What is this "syndrome" that today's geneticists are so concerned about?

 

Breaking Bad: DNA

To understand the problem, you must understand a bit of genetics. You probably know about mutations - bits of DNA that are not replicated perfectly or are perhaps damaged by some environmental toxin. If the mutation is dominant and affects some vital process, it is removed from the gene pool by natural selection when that individual fails to pass its genes on to the next generation successfully. But many mutations have no ill effects because their paired, dominant allele functions normally. These "recessive" mutations are silent in the genome and can be passed to the next generation the same as any other gene, and as long as the offspring has a copy of a normal allele the mutation remains silent. The mutation becomes a problem when an individual inherits two copies so is homozygous at that locus. Without at least one copy of the normal, unmutated allele, the gene does not function properly, and the consequence can range from something relatively trivial (e.g., a different eye color, or slightly shorter legs) to the catastrophic (e.g, blindness, disruption of a critical biochemical pathway, cancer).

 

Mutations happen all the time. The ones with immediate ill effects are removed from the gene pool by natural selection, while the recessive, silent ones remain in the genome as the "genetic load". Every dog - in fact, every organism - has its own unique collection of damaged alleles that causes no harm as long as there is also a copy of a normal allele of each that can do the job it is supposed to.

 

A Star is Born

Now consider what happens in a population of purebred dogs. Let's pretend that this cute collection of dogs represents your breed, with the phenotypic variations among them representing the nuances of type that would be obvious to a serious breeder. We've given each dog a (typographic) recessive mutation, a bit of DNA damage that is not expressed so it has no detrimental effect on the dog. If each dog in our population has a litter of puppies this year, the frequencies of these various alleles in the population will stay about the same in the next generation.

 

But what happens if one of these dogs wins big at an important event and becomes a star? If it's a bitch, she will have a litter of much sought-after puppies, and it will probably be at least a year before she is bred again.

 

But if our star is male (let's call him "Hank"), he will be bred many times and produce dozens (or more!) puppies in a single year. Hank will pass half of his genes, both good and bad, to each of his offspring, so many copies of his recessive, silent mutations get distributed in his puppies.

 

As long as Hank's deleterious mutations are paired with a normal allele in his puppies, they are not expressed and cause no ill effects. But if you could view the gene pool of the breed in the new generation, you would see that now it is markedly different.

 

Hank's mutation has in just a single generation gone from being rare to common, and now lurks silently in the genomes of dozens of his offspring. In this generation, noone is any the wiser. The prized puppies that carry their sire's recessive mutation will appear to be no different than the ones that don't.

 

The Next Generation...

But in the next generation we start to see the first hint of trouble. Perhaps there were a few half-sib matings, or father-to-daughter, and some puppies are produced that are homozygous for Hank's mutation. Perhaps the mutation is lethal and these are stillborn pups, or maybe the puppies are born with a disease. But the breeders will be mystified - they have never had this problem in their line, or even in the breed, so maybe it's just bad luck? Nobody can see yet that this is just the tip of the iceberg.

 

In one more generation, however, the trouble really begins. Carriers produced by the first generation will pass on the mutation to half of their offspring, and half-sib matings or line breedings back to the sire will begin to produce affected puppies. Even while the number of affected puppies is still relatively small, the number of carriers will by now be significant, and remember that our popular sire probably continues to produce more than his fair share of the offspring in each generation. You can see where this is headed. The seeds have been sown.

 

Every litter produced by this popular sire is one less reproductive opportunity for any of the other potential sires in the breed, so the frequency of genes carried by those unused sires will decline in the population. At the same time, multiple bitches are producing puppies sired by Hank that will be half-sibs to the dozens of other puppies in their generation. The temptation to capture a bit more of that popular sire's star qualities will probably result in a few line breedings that will put carrier with carrier.

 

Uh-oh, We've Got A Problem

This is about the time breeders begin to notice that there is a "problem" in the breed. It won't take a pedigree sleuth to trace the growing population of affected dogs back to Hank, our popular sire who will now be blamed for introducing this new disease into the breed. Geneticists will be called in to hunt for the defective bit of Hank's DNA and to develop a reliable test. Then breeders will begin the mission of trying to eliminate Hank's formerly valuable genes from the gene pool, with proportional collateral damage to the genetic legacy of all of the bitches he was bred to. The genetic carnage resulting from attempts to purify the breed of the unfortunate mutation will continue for generations. The ultimate damage to the gene pool can be catastrophic.

 

This happens over and over again in breed after breed. Of course, the problem isn't poor Hank. Wind back the clock, and if the judge had pointed to a different dog at that fateful show - let's say it was Rosco who got the nod - the trajectory of the breed would have been completely different but the consequences pretty much the same. Rosco will leave his genetic legacy behind in dozens of lovely puppies, half of which will have that one nasty mutation that will emerge a few generations down the road to bite the breed. Breeders will eventually catch on, sound the alarm, and the effort to identify and eradicate the offending mutation will begin. The gene pool will be purged, and the next time a big winner appears that happens to be male, the cycle will begin anew.

 

The Unfortunate Legacy of the Popular Sire

The really unfortunate thing about the Popular Sire is that the negative genetic consquences of his popularity don't begin to manifest for generations, by which time the breed already has a really significant problem. The large number of breed-specific disorders known to be caused by a single recessive gene (175 as of this writing; OMIA) is testimony to the prevalence of the problem (indeed, some breeds now suffer from multiple recessive genetic disorders).

 

Of course, it is not just the recessive mutations that are disseminated widely by popular sires. Any genetic disorder can become quickly widespread, especially in the absence of any means of documenting the appearance of a new disease and if breeders are not willing to be completely transparent about issues they are aware of. Unacceptable aggression in English Springer Spaniels, which used to be one of the most popular family dogs in the US, appears to be genetic and has been traced to one popular sire from a prominant kennel (Reisner & Houpt 2005; Duffy 2008). Twenty-five percent of Bernese Mountain Dogs die at an average age of only 8 years old from histiocytic sarcoma (Dobson), a fatal cancer that apparently originated from a single dog in Switzerland, and the flames were fanned by a prolific great-grandson in the US that spread the malignant genes far and wide in the gene pool (Dobson 2013; Moore 1984; Moore & Rosin 1986). Many Dobermans die at an early age from sudden heart failure caused by dilated cardiomyopathy, which can be traced to seven popular sires in the 1950's, three of which died of heart failure (http://bit.ly/1anuinN). A serious - usually lethal - susceptibility of Miniature Schnauzers to infection by Mycobacteria avium (referred to as "MAC" for Mycobacteria avium complex) is thought to be traceable to a sire popular in the mid-1980s and is found now in dogs all over the world (http://bit.ly/1gZbGy7; http://bit.ly/1ciVxNP). There are no doubt many other similar examples that I am not aware of or have never been documented.

 

Leroy (2011) has identified popular sires as the single most important contributor to the dissemination of genetic diseases in purebred dogs. Recognizing this, the FCI has issued a recommendation to breeders that no dog should have more offspring (presumably in its lifetime) than equivalent to 5% of the number of puppies registered in the breed during a five-year period, and a number of national kennel clubs have followed suit (e.g., Finland). But without cooperation of breed clubs, or in the absence of some authority that would oversee registrations and be in a position to police such a breeding restriction, it is hard to see how such a recommendation would have any effect at all on current breeding practices. (Which 5-year period? Which population of dogs - the worldwide breed, or just the dogs in your country? Who does the counting - the owner of the sire, the owner of the bitch, the breed club, the kennel club??).

 

The only people benefitting from the explosion of breed-specific genetic disorders are the molecular geneticists, who have discovered dogs as an ideal research animal because many of the same disorders occur in humans (Ostrander 2012). But as useful and fascinating as dogs might be for their research, I suspect all would prefer to see dogs that are free of genetic disease, for they have so much more to offer in the family home than in the lab.

 

Dobson, JM. 2013. Breed-predispositions to cancer in pedigree dogs. ISRN Veterinary Science 2013: (doi: 10.1155/2013/941275)

Duffy, DL, Y Hsu, JA Serpell. 2008. Breed differences in canine aggression. Applied Animal Behaviour Science 114: 441-460.

Haynes, W. 1915. Effect of the popular sire. Journal of Heredity 6: 494-496.

Leroy, G. 2011. Genetic diversity, inbreeding and breeding practices in dogs: results from pedigree analyses. Veterinary Journal 189: 177-182.

Leroy, G & X. Rognon. 2012. Assessing the impact of breeding strategies on inherited disorders and genetic diversity in dogs. Veterinary Journal 194:343-348.

Moore, PF. 1984. Systemic histiocytosis of Bernese Mountain Dogs. Veterinary Pathology 21: 554-563.

Moore, PF & A Rosin. 1986. Malignant histiocytosis of Bernese Mountain Dogs. Veterinary Pathology 23: 1-10.

Ostrander, EA. 2012. Both ends of the leash- the human links to good dogs with bad genes. New England Journal of Medicine 367: 636-346.

Reisner, IR. & KA Houpt. 2005. National survey of owner-directed aggression in English Springer Spaniels. Journal of the American Veterinary Medical Association 10: 1594-1603.

Wellman, R. & J. Bennewitz. 2011. Identification and characterization of hierarchical structures in dog breeding schemes, a novel method applied to the Norfolk terrier. Journal of Animal Science 89: 3846-3858.

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We have seen the enemy and it is us. As long as people hide their heads in the sand and ignore learning the health behind their lines this situation (which IMHO is NOW) will only get worse. Fortunately there are some very nice working dogs out there where few people ever see them. However there are some problems in the breed that are ignored. EOD is on the increase and PDA is in some very popular lines. These are but 2 problems in the breed. At least work is on PDA

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This is the first I've heard of PDA being a problem in the breed? Of course, I just learned about IGS, but do you have any references that provide statistics on PDA? Just curious, because I actually had to look it up to find out what it is.

 

J.

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Not Pam, but I know litters that had affected pups. Some of the dogs died quite young. One was lucky enough to have surgery to repair it. It is definitely running in bloodlines (two that I know of). No idea of actual prevalence in the breed. One sire and one dam in particular seem to be linked to it. I worry that people will be line breeding on that sire and wonder how many people actually know that he produced it when crossed with several different bloodlines.

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I answered my own question with a quick search, landing on the Universities Federation for Animal Welfare site (UFAW is a charity based in England): http://www.ufaw.org.uk/PATENTDUCTUSARTERIOSUSBORDERCOLLIE.php

 

Here's the text from that page:

 

Summary of Information

(for more information click on the links below)

1. Brief description

Patent ductus arteriosus (PDA) is the most common congenital, hereditary heart abnormality of dogs (Patterson 1971, Bonagura & Darke 1995, Rishniw 2004a). Border collies are predisposed to it (Patterson 1971, Bonagura & Darke 1995, Rishniw 2004a, Stafford Johnson 2006). It frequently leads to an overload of blood on the left side of the heart, which can progress to heart failure and death.

In the foetus, prior to birth, a blood vessel – the ductus arteriosus – is present providing a short cut for blood from the pulmonary artery to the aorta without going via the lungs (as these are non-functional prior to birth). This vessel should close at birth. In this disease (patent ductus arteriosus) it does not.

The commonest reason for this failure in dogs is a hereditary lack of the smooth muscle in the vessel wall that should close it (Rishniw 2004a). When it fails to close, the result is that, during normal circulation, blood shunts from the aorta to the pulmonary artery, because the blood pressure is higher in the aorta compared with the pulmonary artery. Small shunts cause few problems (Kittleson 1998, Bonagura & Lehmkuhl 1999), but when the vessel is wide enough to allow large shunts, there is significant overload of blood flow to the left ventricle and, with time, left-sided heart failure develops.

Left-sided heart failure causes lethargy and inability to exercise, with weight loss and difficulty in breathing. There may be coughing and rapid breathing, and as the disease progresses, dogs show marked signs of respiratory distress, and may collapse or die suddenly. Most have to be euthanased due to respiratory distress at some stage.

PDA is usually treatable and, in most cases, curable if identification and intervention occur early.

 

 

2. Intensity of welfare impact

Except in mild cases, in which there may be no welfare consequences, this disease causes left side heart failure. This leads to fluid accumulation in the lungs which makes breathing difficult. Affected dogs are likely to feel unwell and be unable to exercise normally.

As heart failure progresses and the pulmonary fluid accumulates further, breathing becomes an increasing struggle, which is likely to cause severe distress and discomfort and, unless euthanased, the dog effectively dies from drowning in its own body fluids.

Diagnostic and therapeutic procedures may have some adverse welfare effects in some dogs.

 

 

3. Duration of welfare impact

The defect is present from the time of birth and some puppies show signs of heart failure when as young as eight weeks of age (Stafford Johnson 2006). A large proportion of affected dogs (64%) die within a year of diagnosis (Eyster et al 1976). The time course of the disease, and the period when welfare is affected, tends therefore to be occur over months to years.

 

4. Number of animals affected

Although Border collies are predisposed to PDA (Patterson 1971, Bonagura & Darke 1995, Rishniw 2004a, Stafford Johnson 2006) and it is seen “relatively commonly” within the breed (Stafford Johnson 2006) we are unaware of data on the proportion of collies that are affected by PDA.

Patent ductus arteriosus (PDA) is stated, by some, to be the most common congenital (present at birth), hereditary heart abnormality of dogs, accounting for 25 to 30% of these cases (Patterson 1971, Buchanan 1999, Slater 2003, Rishniw 2004a).

 

5. Diagnosis

Detection of a continuous, “machinery” heart murmur in any young dog is highly likely to indicate PDA (Stafford Johnson 2006, Brownlie et al 2010). Confirmation is usually made using colour-flow Doppler ultrasonography.

6. Genetics

PDA has been shown to be a polygenic threshold trait in poodles (Patterson et al 1971) and it is likely that it is inherited in this way in other predisposed breeds (Patterson 1989, Bonagura & Darke 1995). That is, it is thought that multiple genes are involved in the disease and that the severity of the defect and the disease consequences seems to be directly related to the abnormal genetic burden in each individual (Patterson 1989; Rishniw 2004a).

 

7. How do you know if an animal is a carrier or likely to become affected?

Most affected individuals can be detected early in life by listening to the heart (auscultation) with a stethoscope during veterinary examination. All puppies should have a veterinary examination prior to purchase. It is not known whether animals can carry the genes that cause the condition without developing the disease themselves, although this seems likely, and there is no way to detect such carriers at present.

8. Methods and prospects for elimination of the problem

As far as we are aware, there are no breeding programmes aimed at reducing the prevalence or eradicating PDA from the Border collie breed.

Bell (2010) suggests the assignation and use of breeding values when tackling suspected polygenetic disorders, which take account also of the prevalence of the disease in close relatives. In developing breeding strategies to tackle particular genetic diseases it is important to take account of others also and to avoid further inbreeding that might result in new genetic risks (eg where necessary, by crossing with other breeds).

So it seems that this is another polygenic disease for which there will be no ready test. I wonder what the prevalence is here in the U.S.? Clearly a dog with at least the serious form of this condition wouldn't be able to work (or do sports), so I wonder if people would actually be breeding from these dogs? Can you name working lines with PDA?

People are talking more openly about EOD, at least as far as I can tell. I am aware of at least some (if not all) lines in which it is found. Although it has been found not to be a simple recessive, it still seems fairly possible to control its incidence through breeding practices. But PDA seems to be more like epilepsy, where you can combine two lines with no apparent incidence of the disease and those numerous genes come together just right to create a pup with PDA. But as far as I can tell, it would be next to impossible to predict that. The best you could do is not breed affected dogs, but as with epilepsy, you could breed a dog who had produced it with a dog who hadn't produced it and hope the odds were in your favor that the non-producer doesn't have the exact genes needed to produce epilepsy in combination with the dog who did produce it. Am I making sense?

So I see two issues (with PDA specifically and with polygenic diseases in general):

1. Is PDA or [name of polygenic disease] really being swept under the rug (especially with PDA since it seems to manifest--that is, be detectable--very early, compared to something like epilepsy, which can appear as late as 6 years0?

2. Aside from acknowledging its existence (by virtue of the fact that a particular cross produced it), what can one really do with a disease that is truly polygenic in nature if one can't test for all of those genes (which also mean knowing what combinations of those genes actually produce a disease and whether at least some of those genes also confer (or contribute to that conference) of beneficial traits?

Just musing out loud here....

J.

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Thoroughbred Horses are a good place to look to really study the popular sire effect - the records are so good and the results so obvious.

 

I am learning in order to take over a private breeding program that needs to make sure at least 20 healthy, usable dogs are always in the right age bracket. My great grandfather was a science-guy and so we were lucky to have avoided any line breeding issues and regularly enough (from a genetic perspective) add new blood so that we have maintained a fairly healthy and vigorous population.

 

It is my understanding, based on the many breeding notebooks I have been reading (almost through the NINE boxes now), that this was accomplished by being able to track dogs through their lives through many contiguous generations. As noted, sometimes whole lines were abandoned because three or four generations in, litters with this or that commonality were faring badly.

 

It is very important, in my mind, that, for the sake of the breed, the trial/public lines and the farm/private lines do not continue the trajectory they are on - which is one of division. More trialers have to farm and more farmers have to trial and those dogs have to get busy with each other.

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People are talking more openly about EOD, at least as far as I can tell. I am aware of at least some (if not all) lines in which it is found. Although it has been found not to be a simple recessive, it still seems fairly possible to control its incidence through breeding practices.

Julie,

Where is the information that EOD is not a simple recessive?

Mark

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CMP, You are very fortunate to have detailed pedigree and breeding info from your great-grandfather onwards, but I have a few queries (and yes, these are honest queries based on my interest in genetics and sheepdogs rather than any wish to 'get at' your family's breeding decisions)

 

1. When breeding sheepdogs, does your family just look for the "ideal" dog/bitch or do they also somehow also consider the partnership between handler & dog? I ask this because surely a dog that suits one handler's working style may not suit another.. and does this effect the breeding decisions?

 

2. What characteristics does your family consider make up the 'ideal' sheepdog? (if there is one)?

 

3.I presume that even within a "perfect mating" that not all pups in a litter will meet the grade, so what number of pups do you need to produce per year in order to have "at least 20 healthy, usable dogs are always in the right age bracket"?

 

3. Do you cross in any other herding dogs to produce your sheepdogs or does your family use only BCs?. If you just use BCs, then how do you know that any 'new blood' dogs do not go back to the same lines that your family already use?

 

4. If I understand your other posts, you also breed Burnese Mountain Dogs. My (limited) understanding of this breed is that they have a number of genetic disorders... what breeding decisions do you take to minimise these?

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Julie,

Where is the information that EOD is not a simple recessive?

Mark

hi mark there was this paper by Sheila M Schmutz. In it, she says 'A similar mating of two deaf parents in Family 1 (Figure 2) suggests that not all pups will necessarily be deaf, excluding an autosomal recessive pattern of inheritance.

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So if I'm understanding you correctly Liz, there is a sire (or sires) who are known (at least by some people) to have produced it , but I'm assuming not on every cross made to that particular sire? So would you propose removing that sire from the breeding pool (based on your comments about epilepsy, I'm guessing the answer is yes)? What about the dams who produced it? And what if they produced it just once, when bred to a particular dog, but not when bred to another dog (same goes for the sire)? Can any correlations be drawn between a "producer sire" and the bloodlines of the bitches in combination with which PDA was produced? (That is, if you're saying that one particular sire has produced PDA on more than one occasion, is there any connection among the bitches who produced it with that particular sire?)

 

From the tiny bit of reading I've done, it really sounds as if PDA parallels epilepsy when it comes to breeding choices, and right now at least the ABCA health and genetics committee is saying that you simply don't repeat breedings that have produced the disease. I think one could extrapolate from that the idea that you probably don't want to breed either sire or dam that produced that disease to a dog closely related to the dog with which it produced the disease, but beyond that I don't see how you can make a decision to remove a dog (or dogs) from the gene pool. Maybe I'm missing something.

 

J.

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hi mark there was this paper by Sheila M Schmutz. In it, she says 'A similar mating of two deaf parents in Family 1 (Figure 2) suggests that not all pups will necessarily be deaf, excluding an autosomal recessive pattern of inheritance.

The problem with the data in Figure 1 is it does not list the ages of the offspring in Family 1 for the readers to know if perhaps they could still go deaf (based upon the quote from this article, dogs with no ages listed were not BAER tested). We also still don't know the genetics that control the age of onset of deafness.

 

2052-6687-1-6-2.jpg

 

 

In another portion of this study, three families of Border Collies showed a pattern of adult onset deafness. Some dogs were BAER tested at more than one age, but most were tested only at the age indicated in Figure 2. However, the dog in Family 3 who is shown as deaf at 3 was based on owner report only. Not all BAER tests were conducted by the same veterinarian.

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Mark,

My apologies: I was using shorthand. My understanding is that inheritance of EOD doesn't follow a simple recessive pattern, probably because of modifier genes. I gained that understanding from information you have posted here on the EOD study that attempted to identify and create a test for that recessive gene, based in the understanding that the study was not successful in identifying a single gene (or small group of genes) that could be tested for. Perhaps I misunderstood.

 

CMP,

You are basing a lot of your comments in this section and others on your view that trial dogs are bred exclusively to trial dogs and farm dogs exclusively to farm dogs, despite the number of folks here who have actually done matings that are not in keeping with your worldview. My own working dogs have trial lines and strictly working lines combined (to make that perfectly clear, there are dogs close up and way back in my dogs' pedigrees who worked on farms and never saw a trial field, and there are others who did a lot of trialing and some who did both). You are course are welcome to continue to believe that people who trial breed their dogs only to the dogs of other people who trial, but I am telling you that in my experience you are making a faulty assumption and then basing a whole lot of conclusions on that faulty assumption, as someone who neither breeds, nor works, nor trials dogs. Maybe if you spent some time in the larger community of people who trial dogs you'd be pleasantly surprised, but you might also have to change your firmly held beliefs about what you know.

 

J.

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I did not say that all dogs that have connections to epilepsy should be removed from the gene pool. I said that everyone needs to decide on their own comfort level with the disease. And given the newest research, I am comfortable with the recommendation of not breeding affected dogs but keeping their relatives in the gene pool.

 

See my above post about the sire producing PDA. I said I was concerned about line breeding on him, which would be foolish IMHO. I would say the same about a stud dog that produced epilepsy. Line breeding on such a stud dog would be asking for trouble.

 

The dam that produced a high incidence of PDA when crossed with a variety of lines was owned by MAH. (Can we really be certain of accuracy of pedigree though?) I wouldn't buy a dog with MAH's name on the papers anyway, so I have no problem avoiding her.

 

I can give you names of owners who had pups and grandpups going back to the popular sire if you would like to ask them for information.

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Julie,

It is my understanding the inheritance is likely recessive (not proven); this is for whether or not the dog will go deaf before old age deafenss. There are likely additional gene(s) which also control the age of onset.

Mark

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True... but given the number of genetic causes of non-syndromic deafness in humans, IMO it would not be surprising if there was also a several different genetic defects underlying EOD in border collies as well. So it may prove necessary to assign deaf dogs to different groups (e.g based on the age of onset ETA i.e. more than just younger than 'geriatric').

 

Alternatively as Julie says in her post, there could be a single genetic mutation with other modifiers involved.

The problem with the data in Figure 1 is it does not list the ages of the offspring in Family 1 for the readers to know if perhaps they could still go deaf.

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Such as is proposed by the PI of this study

 

 

Variation in Genes Related to Cochlear Biology Is Strongly Associated with Adult-Onset Deafness in Border Collies

 

Association modeling suggested an autosomal recessive mode of inheritance for adult-onset deafness in Border Collies.

Which also indicated

 

Our results represent the first GWAS of adult-onset deafness in the domestic dog. We demonstrated the successful application of target capture for next-generation sequencing (NGS) in the dog. The region implicated by GWAS in our study is syntenic to regions implicated in congenital sensorineural deafness in humans.

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The link is to the full article which you can read. You review of it may revel things that the H&G Committee members have missed.

 

What we need for EOD is a comprehensive assessment of inheritance which we could obtain from a survey on deafness where we get a significant percentage of participation; and we need a genetic test.

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would it help to set up regional and local BAER testing clinics at trials, not only testing dogs trialed but also asking for retired dogs, breeding stock and the using farm dogs that are not normally coming to the trials?

 

Would there be ABCA funding available to help reduce the expense of the clinic to help encourage more to test dogs, even dogs they wouldn't normally test if they were considering the financial commitment.

 

There is someone here in Iowa who is also licensed in NE, he said he will come to a event and do a clinic, I think he told me $40 a dog but I don't know what his other charges would be to get him there.

 

At least that way maybe the population can get charted a bit to see if other families of dogs have a higher rate deafness or if it is seen less or more in certain areas.

 

My thought would be to have a broad sample of dogs and genetics not just those that are at higher risk since the results will inevitably be used by some when they are selecting or buying.

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There was a BAER clinic at the finals this year.

 

There are more basic questions about BAER testing that we (the committee) need to address.

 

I will strongly recommend additional ABCA funded BAER testing as long as those receiving the tests are required to turn in a completed confidential health survey to the ABCA.

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Liz,

I was remarking based on past comments you have made here and elsewhere that you were not comfortable breeding from close relatives of dogs who have produced epilepsy. It appears that with additional research information you have changed your personal beliefs about breeding and epilepsy. And I agree with you that people need to come to their own comfort level regarding such breeding decisions.

 

My questions about PDA weren't meant to "out" the stud or any bitches. I was simply comparing it to epilepsy and wondering if breeding decisions wouldn't be made similarly. I guess my real question would be: Are people line breeding to the stud in question (including line breeding)? Are the close relatives of offspring being bred? If the pups don't have any evidence of a shunt, would we simply assume that they may be carriers of at least some of the genes responsible (or not) and breed accordingly (knowing that it could be something of a crap shoot since one can't know what genes a potential mate might carry)?

 

I just wonder about the constant accusations (not by you) that people make about genetic issues being a big problem in working border collies and people hiding that information. Note that I am not saying these problems don't exist, nor that they aren't important, but every time I hear of a new issue, the first thing people seem to want to say is that breeders are hiding that information. And yet I see a lot of folks actually talking about this now. I think that's a good thing, and I hope more people will come forward and make clear when their own breeding choices have produced problems. If you know about this particular stud, surely other people do too?

 

From my reading, it seems that one should be able to avoid breeding from any dog affected by PDA; if the dog has gotten regular vet care then it's likely the condition would be recognized and, unlike epilepsy, it's obvious from birth that the dog has the condition, so there certainly shouldn't be any reason for people to unknowingly breeding affected dogs.

 

Anyway, sorry to ramble a bit: I do get what you're saying about line breeding. I just got a puppy who is the daughter of the littermate to my Twist. Twist produced epilepsy, as you know. But I am hoping that the combination with that particular sire was the problem, since any number of Twist's relatives have been bred multiple times with no issues. Time will tell if my gamble paid off....

 

J.

 

I did not say that all dogs that have connections to epilepsy should be removed from the gene pool. I said that everyone needs to decide on their own comfort level with the disease. And given the newest research, I am comfortable with the recommendation of not breeding affected dogs but keeping their relatives in the gene pool.

 

See my above post about the sire producing PDA. I said I was concerned about line breeding on him, which would be foolish IMHO. I would say the same about a stud dog that produced epilepsy. Line breeding on such a stud dog would be asking for trouble.

 

The dam that produced a high incidence of PDA when crossed with a variety of lines was owned by MAH. (Can we really be certain of accuracy of pedigree though?) I wouldn't buy a dog with MAH's name on the papers anyway, so I have no problem avoiding her.

 

I can give you names of owners who had pups and grandpups going back to the popular sire if you would like to ask them for information.

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Julie, I am glad you never had to go through that, but it's happened to many of us far too often. SOME breeders are very honest and happy to share info. Others hide health problems to protect their bottom line.

 

Here is just one example: I bought a bitch. When she was 5 years old I decided she was worth breeding. I did a lot of research on the health of her relatives, including calling her breeder. The owners of the stud I was considering using were honest with me that an ancestor had gone deaf. I told this to my bitch's breeder, asking if any relatives had gone deaf. I was assured that this was not the case. Fast forward 4 years and one of the pups from my litter went deaf (EOD). I had to find out from other people that my bitch's dam went deaf at about age 6 (she would have been about 12 years old when I called the breeder to ask about it).

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Liz,

I didn't say that no breeders ever hide things. I said that I don't believe it's as rampant as some state it seems to be. Maybe I'm wrong, but I'd like to think I'm not. And for those who are lying about the issues in their breeding stock, I'd hope the people who have gotten affected dogs from them would put the word out so that others can have the hope of not suffering from the same fate.

 

J.

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