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BOB Collie at Westminster sired by a double merle

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Let's play devils advocate for a moment.

 

Is there any difference between breeding a deaf MM Collie because it has superior breed attributes that you wish to increase in the breed vs. breeding a CEA "go normal" (i.e. CEA affected) working Border Collie because of its superior working ability?

 

The main difference here that I see are the breeding goals: structure vs. working ability.

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Let's play devils advocate for a moment.

 

Is there any difference between breeding a deaf MM Collie because it has superior breed attributes that you wish to increase in the breed vs. breeding a CEA "go normal" (i.e. CEA affected) working Border Collie because of its superior working ability?

 

The main difference here that I see are the breeding goals: structure vs. working ability.

 

Form follows function, I guess...or at least should. If that function is to be pretty and stoopid, then I guess that's what you breed for.

I, however, would question your priorities.

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"Is there any difference between breeding a deaf MM Collie because it has superior breed attributes that you wish to increase in the breed vs. breeding a CEA "go normal" (i.e. CEA affected) working Border Collie because of its superior working ability?"

 

I am under the impression that the goals are different in that breeding a CEA affected dog with normal vision to a clear dog allows the good qualities of the affected dog to remain in the gene pool with the ultimate goal of reducing the incidence of CEA by slowly breeding away from it without narrowing the gene pool. I don't see how that can be the aim of breeding Mm to either Mm or MM since the merle color which itself is directly linked to various health problems is the very quality valued. Unlike CEA, it is not possible to breed past merle related problems because merle is the desired outcome.

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Penny, are you claiming there are health issues with Mm?

According to Prevalence of Deafness in Dogs Heterozygous or Homozygous for the Merle Allele the rates of deafness in Mm are 2.7% uni and 0.9% bi. Are these really that different than the rates of deafness in Border Collies or other breeds?

 

Prevalence of Unilateral and Bilateral Deafness in Border Collies and Association with Phenotype

Hereditary Deafness in Dogs and Cats: Causes, Prevalence, and Current Research

 

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Let's play devils advocate for a moment.

 

Is there any difference between breeding a deaf MM Collie because it has superior breed attributes that you wish to increase in the breed vs. breeding a CEA "go normal" (i.e. CEA affected) working Border Collie because of its superior working ability?

 

The main difference here that I see are the breeding goals: structure vs. working ability.

I think that there is a difference, but I think both are poor choices.

 

A deaf double merle should not be bred because it is a double merle (and should not have been created in the first place.)

 

A Border Collie with "superior working ability" but CEA affected would not be my choice for breeding, even when mated with a normal-eyed dog/bitch. But a dog with "superior working ability" is a bit different than a deaf show dog. At least the Border Collie can do the job it was bred for. A deaf Collie cannot be shown. (Which is presumably what it was bred for.)

 

Both the CEA affected Border Collie and the deaf double merle Collie are themselves blameless, but their breeders are not. Especially the breeder of the Collie.

 

My understanding is that two normal-eyed dogs when mated can produce offspring affected with CEA. (Perhaps this can be avoided with DNA profiling, but I don't know much about that.) But the breeder who puts together two normal eyed dogs certainly would not be expecting to produce CEA affected pups.

 

But a deaf double merle Collie is a different story. What can you breed him to without running the risk of creating defective pups? If you breed him to a sable you will likely get sable-merles, which are a "disallowed color." If you breed him to a merle, you will get more double merles. If you breed him to a tri, you will get a bunch of merles. And while I don't think either merles or sable merles should be "disallowed," neither do I think you should breed for them intentionally.

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While you look into it I'm going home and will check back tomorrow.

 

Just to be clear, I have serious issues with breeding dogs that are affected with a genetic disease; however, there has been discussion of breeding CEA affected working Border Collies when they have very desirable working traits (I would set the bar VERY high for wanting to breed a CEA affected dog) . Ignoring the differences between breeding for form vs. function, I'm trying to ascertain if there really is a philosophical difference between breeding an MM Collie or a CEA Affected working Border Collie.

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This paper (Prevalence of Unilateral and Bilateral Deafness in Border Collies and Association with Phenotype, J Vet Intern Med 2006;20:1355–136) describes a study of the prevalence of deafness in border collies. BAER testing was done on 2,597 border collies and border collie puppies in the U.K. The conclusion is that, yes, there is an association of deafness with merle coloration. They discuss the phenotypes of the tested dogs, but not the genotypes, so probably most of the merles were heterozygotes (Mm).

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Let's play devils advocate for a moment.

 

Is there any difference between breeding a deaf MM Collie because it has superior breed attributes that you wish to increase in the breed vs. breeding a CEA "go normal" (i.e. CEA affected) working Border Collie because of its superior working ability?

 

The main difference here that I see are the breeding goals: structure vs. working ability.

 

The difference is that they intentionally created the double merle dog, knowing that there would be an extremely high likelihood of health problems and knowing that the dog produced would most likely not be functional for the stated breeding goal (in this case competing in the show ring).

 

Your example of the 'go normal' dog would only be a similar circumstance if he was produced by intentionally and knowingly breeding together two parents who would be expected to produce CEA affected pups who had a high liklihood of being nonfunctional for their intended purpose of working livestock. The fact that the dog became a 'go normal' and ended up functional would be just pure luck, as I don't believe current genetic testing can tell you to what a degree a genetically effected dog will actually express the disease.

 

The problem I see is not so much in using the affected dog for breeding (although I'm not saying that's okay either) but in intentionally creating such a dog in the first place.

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The problem I see is not so much in using the affected dog for breeding (although I'm not saying that's okay either) but in intentionally creating such a dog in the first place.

 

This.

 

I am assuming the go normal was created by accident in the days prior to DNA testing.

 

Now, if the breeder of that dog produced it by mating two KNOWN carriers of CEA, I would call that breeding highly irresponsible. Unfortunately, I have heard of such litters even after the testing became available. :angry:

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"Penny, are you claiming there are health issues with Mm?"

 

Don't know yet. Gimme a few minutes.

 

I don't need to make so extravagant a claim for the argument to hold. Let's take the case of CEA go-normals bred with carriers or clears or even affected to affected. The ultimate aim is to breed through CEA without losing other genetic components and narrowing the gene pool. Ethical breeders will do this; however, even from ethical hands dogs will slip through to the mills and people who can't help but breed everything and so on. The number of affected dogs this happens to will decrease gradually and eventually reduce numbers. With merle, that can never happen because merle is the valued quality. That dominant gene has to be there waiting to pounce.

 

Mark, I never for a moment thought were doing anything other than being devil's advocate. That's why I responded in the first place. My position is not based on which goal is preferable although I am comfortable with the value argument as the best. I didn't answer that way because I thought you wanted to avoid that line of reasoning.

 

Concerning merle to merle, I have never heard anyone with working border collies regarding CEA say anything as simultaneously specious and pompous as this: "Doing a merle-to-merle breeding should only be done by experienced and knowledgeable breeders, and only when a suitable non-merle with the desired quality is not available." Of course, I doubt anyone would dare.

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A deaf double merle should not be bred because it is a double merle (and should not have been created in the first place.)

 

What does this mean? Bred to black tri there's no guarantee for defective pups. I agree the creation itself should not have occurred to begin with.

 

A Border Collie with "superior working ability" but CEA affected would not be my choice for breeding, even when mated with a normal-eyed dog/bitch. But a dog with "superior working ability" is a bit different than a deaf show dog. At least the Border Collie can do the job it was bred for. A deaf Collie cannot be shown. (Which is presumably what it was bred for.)

 

How can it *do the job* if it can't see?

 

My understanding is that two normal-eyed dogs when mated can produce offspring affected with CEA. (Perhaps this can be avoided with DNA profiling, but I don't know much about that.) But the breeder who puts together two normal eyed dogs certainly would not be expecting to produce CEA affected pups.

 

Impossible to get anything other than normals if sire and dam are normal (DNA Normal).

 

But a deaf double merle Collie is a different story. What can you breed him to without running the risk of creating defective pups? If you breed him to a sable you will likely get sable-merles, which are a "disallowed color." If you breed him to a merle, you will get more double merles. If you breed him to a tri, you will get a bunch of merles. And while I don't think either merles or sable merles should be "disallowed," neither do I think you should breed for them intentionally.

 

You can breed him to anything other than a merle. The only place the colors you speak of are *disallowed* is the conformation ring.

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Another sad note: I recognize the name Laura Rizzo. If this is the same person, then this is a case of going over to the dark side.

Penny,

I was wondering the same thing. She was active trialing when I was just starting out. I wonder if it really is her?

 

J.

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What Liz P said:

 

I am assuming the go normal was created by accident in the days prior to DNA testing.

 

Now, if the breeder of that dog produced it by mating two KNOWN carriers of CEA, I would call that breeding highly irresponsible. Unfortunately, I have heard of such litters even after the testing became available

 

In either the case of the double merle or the known CEA dogs I'd have to wonder if there was not a breeding choice as good or better than the affected dogs and why would one choose an affected dog over a non affected if an equal or better is available?

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What does this mean? Bred to black tri there's no guarantee for defective pups. I agree the creation itself should not have occurred to begin with.

 

But there's no guarantee there won't be either, is there?

How can it *do the job* if it can't see?

 

The original comparison was between a dog with "superior working ability." I would presume that a dog with superior working ability could see. Do dogs with CEA always go blind? Are there "carriers"?

 

Impossible to get anything other than normals if sire and dam are normal (DNA Normal).

 

Perhaps my understanding of CEA is wrong. I am working with old information, but I understood that a dog was rated normal, or grade 1-4 on the strength of an eye exam. I also thought that there were carriers which could pass an eye-test as normal.

 

You can breed him to anything other than a merle. The only place the colors you speak of are *disallowed* is the conformation ring.

 

Again, the original comparison was between a show Collie and a working-bred Border Collie. It was a given that the Collie in the comparison was a show dog. But to avoid the possibility of producing dogs that could not be shown, (ie a sable-merle or a deaf or blind merle) it would be pretty useless for it to be put to anything but a tri. (And even breeding it to a tri would be a bad idea to me. If memory serves me, you could still get merles, and merles frequently have problems with skin and coat as well as the blindness & deafness that happens when you double them up. In my experience they are more prone to flea-bite allergy dermatitis and more susceptible to "Collie nose" and other sunburn issues.)

 

I don't think of a breed-ring dog's calling as work at all. But it was stated as a given in the original devil's advocate scenario that the Collie was a show dog. I think this was a purely academic comparison to begin with, and simply thrown out to stimulate discussion.

 

I've given up on "Lassie Collies" altogether at this point in my life. But the last one I owned was a completely healthy sable-merle male. (He had brown eyes and only a few tiny patches of blue on his ears - otherwise he looked like a normal shaded sable.) He never sired any pups, but I was interested in the color genetics of the breed. The knowledge of both color genetics and inherited disorders have come a long way since the '80s. But I haven't kept up with them, as I decided a long time ago that I would not be breeding dogs of any kind in the foreseeable future - if ever. But the subject came up here today and I was interested. If I am wrong, I'm happy to be corrected! :)

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Penny, are you claiming there are health issues with Mm?

According to Prevalence of Deafness in Dogs Heterozygous or Homozygous for the Merle Allele the rates of deafness in Mm are 2.7% uni and 0.9% bi. Are these really that different than the rates of deafness in Border Collies or other breeds?

 

Prevalence of Unilateral and Bilateral Deafness in Border Collies and Association with Phenotype

Hereditary Deafness in Dogs and Cats: Causes, Prevalence, and Current Research

 

 

 

Hi Mark. I really shouldn't be spending time here, as I have work up to my eyeballs. But having checked in...I've seen studies that suggest Mm isn't a problem as well, but then there is this study that indicates otherwise (looking at the percentages in the Reetz study): http://www.pnas.org/...103/5/1376.full (Retrotransposon Insertion in SILV Is Responsible for Merle Patterning of the Domestic Dog) with an excerpt below:

 

 

 

Dogs having
Mm
and
MM
genotypes typically have blue eyes and often exhibit a wide range of auditory and ophthalmologic abnormalities (
). Reetz
et al.
(
) studied the auditory capacity of Dachshunds and found that 54.6% of
MM
and 36.8% of
Mm
dogs had auditory dysfunction, ranging from mild to severe deafness. All control dogs (
mm
) in the study had normal hearing. Klinckmann
et al.
(
,
) conducted ophthalmologic studies with three groups of Dachshunds (
MM, Mm
, and
mm
) and found that merles and double merles had significantly greater frequencies of ocular abnormalities, including increased intraocular pressure and ametropic eyes. Microphthalmia and colobomas are well described in merle and double merle Dachshunds and Australian Shepherds (
,
,
). In all breeds, the double merle genotype can be sublethal and is associated with multiple abnormalities of the skeletal, cardiac, and reproductive systems (
,
,
). For these reasons, merle-to-merle breedings are strongly discouraged (
).
  1. ,
    ,
  2. ,
    ,
  3. , and
  4. ,

ETA: Sorry Shore's Dog. I only just now saw that you had posted the exact same study and (not surprisingly) the same paragraph.

 

 

 

 

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Double merle breeding. :blink::angry:

 

Actually...ya' got me. I had never seen it in the show world until now. Just another reason to add to my many reasons to be soured on the AKC breed ring. I saw from the GSD judging that most still have over-angulated wobbly rears, as well.

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We have (had) a homozygous merle pup in my shelter until yesterday. She's a sable merle. She has a completely detached retina in the one eye, with a few small colobomas throughout the iris. She has an almost detached retina in the other, with several large colobomas throughout. She's got nystagmus in the one eye that is normally shaped; the other is microthalmic. She's functionally blind. It's pathetic.

 

We don't know what she is, breed wise. She's one of our famous "spotty rez dogs" who seem to get pumped out with some regularity in the area she's from. We assume she's a homozygous merle because the litters of some spotty / some not we get in are always healthy and "normal" across the board for sight and hearing.

 

6884601049_fa520f45cb.jpg

 

6884605059_c16615b8ea.jpg

 

My experience with the merle litters has been that the merle-to-solid breedings, producing both merle and other patterned pups are generally fine. The merle-to-merle breeders generally produce some problem dogs being deaf/blind or both. One litter produced all merle puppies, who were all fine for sight and hearing - but two did die in the shelter prior to our taking them, so that may have been related to the merle/merle, but we'll never know because they died.

 

I think it's very sad. A merle to solid (etc) breeding will produce 25% or more merles with the rest being solid (etc). A merle to merle breeding will produce all merles, but a percentage I can't remember off hand will generally be problematic for sight/hearing. The importance placed on a "perfect" merle is largely what drives breeders to do the double merle breedings - the number of merles will be higher (100%) so the odds of getting a "good" one are higher, but the odds of producing defective pups are also a lot higher. Breeders will argue that they are doing it carefully and conscientiously, but I have trouble with equating "careful and conscientious" with a deliberate production of potentially deaf and/or blind pups.

 

I know one breeder who bred a red dog to a blue merle because they thought they'd get red merles. Le sigh.

 

RDM

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But Gloria, Lassie is not "correct." OMG, one of her ears tips more than the other! Her coat is certainly insufficiently thick and fluffy. And most importantly, her head is not shaped like a long thin cucumber.

 

 

Okay, you made me laugh. :lol: Thanks for a spot of levity in all this.

 

~ Gloria

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Hi Mark. I really shouldn't be spending time here, as I have work up to my eyeballs. But having checked in...I've seen studies that suggest Mm isn't a problem as well, but then there is this study that indicates otherwise (looking at the percentages in the Reetz study): http://www.pnas.org/...103/5/1376.full (Retrotransposon Insertion in SILV Is Responsible for Merle Patterning of the Domestic Dog) with an excerpt below:

The problem with the data in the quoted introduction is it comes from epidemiological studies which do not prove causation, only correlation; these studies did not distinguish between Mm and MM.

 

It you read all the way to the end of the linked PNAS article on the identification of the merle gene you find this which seems to be at odds with the quote from the introduction which implies Mm carries increased health risks.

 

A genetic test for the merle locus can help responsible breeders of merle dogs prevent undesirable double merle progeny by allowing them to (i) distinguish merle from nonmerle in light-colored dogs that show little contrast between areas of dilution and full pigmentation, (ii) classify harlequin Great Danes as single or double merle, and (iii) identify cryptic merles.

Taken in total it seems to me science has not decided if being Mm is unhealthy.

 

 

 

I concede that breeding to produce MM (which is clearly linked to health issues) was inappropriate. My philosophical question was about once you have a MM dog (which could be produced by merle x cryptic merle) is it any different than breeding a go normal dog.

 

 

 

For those of you who don't know, "go normal" is a term used to describe a dog affected with CEA but has little to no loss of vision. Many of you are assuming that every breeder is using the CEA DNA test prior to breeding; reality does not support this assumption.

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This has been an interesting discussion on people's philosophical stand and people's understanding of the state of the science on the merle gene. I certainly don't have all the answers and these exercises help me probe what I know and don't, differentiate it from what I think I know, and how this impacts my stand on subjects.

Thank you all.

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Penny,

I was wondering the same thing. She was active trialing when I was just starting out. I wonder if it really is her?

 

J.

 

Someone in Georgia should know. Trig was a good dog as I recall.

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The problem with the data in the quoted introduction is it comes from epidemiological studies which do not prove causation, only correlation; these studies did not distinguish between Mm and MM.

 

It you read all the way to the end of the linked PNAS article on the identification of the merle gene you find this which seems to be at odds with the quote from the introduction which implies Mm carries increased health risks.

 

 

Actually, that's why I specifically mentioned the Reetz study. That particular study did distinguish between Mm and MM, and in fact found the percentages of Dachshunds affected as follows:

 

Reetz
et al.
(4) studied the auditory capacity of Dachshunds and found that
54.6% of
MM
and 36.8% of
Mm
dogs had auditory dysfunction
, ranging from mild to severe deafness.
All control dogs (
mm
) in the study had normal hearing
. (Clark, Wahl, Reest, and Murphy)

 

 

 

Having been forced to read through all the way through to the end, due to a summary I had undertaken for a course, I did read the last paragraph and found it to ignore the data on the Mm dogs as well. So, I agree with your statement that:

 

"Taken in total it seems to me science has not decided if being Mm is unhealthy."

 

I think that sums it up nicely.

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Actually, that's why I specifically mentioned the Reetz study. That particular study did distinguish between Mm and MM.....

How did the authors in 1977 determine the genotype of these dogs when the gene wasn't identified until 2005? Are the phenotypes in this breed 100% indicative of the Mm and MM genotypes? Is it possible that the differences between dappled and double dappled Dachshunds are just as easy to visually distinguished between as some white and excessive white in Border Collies (see BC hearing study link)?

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How did the authors in 1977 determine the genotype of these dogs when the gene wasn't identified until 2005? Are the phenotypes in this breed 100% indicative of the Mm and MM genotypes? Is it possible that the differences between dappled and double dappled Dachshunds are just as easy to visually distinguished between as some white and excessive white in Border Collies (see BC hearing study link)?

 

 

I am no scientist, so I can only speculate. I do know that MM Dachshunds present with white patches, while those that are Mm do not. Of course that is going by phenotype, so your point is well taken. However, it seems reasonable, given the way the merle presents in Dachshunds, that one would assume merle with no white as Mm and merle with white as MM. Of course, the fact that there are piebald Dachshunds might throw a wrench in that theory.

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