[Josey]

First, let me say, this is *not* a pointed question, I am truly asking because I know less than nothing about breeding.
I am curious, when looking at pedigrees of show dogs from responsible breeders, about the number of times the same dogs show up on both sides of the pedigree. Isn't this inbreeding? Or is it OK if it is 'X' number of generations removed from the actual breeding pair? Is this what the term "line breeding" means?
I've seen Web site from people who don't appear to be responsible breeders advertise that their pups "aren't inbred like show dogs."
Please explain all this to me!

 

[biscuit]

Okay. This is my amateurish attempt at an explanation.

Dog breeds are identifiable as specific breeds because certain traits have been selected for in the process of breeding. As a result, ALL identifiable dog breeds - not simply bassets - are very inbed.

Unfortunately, one of the consequences of being s highly bred is that the risks of transmitting genetically based diseases becomes much, much higher.

Now I don't know the genetics of dogs or whatever, but I'm going to make a guess that a lot of these diseases are recessive traits. So I'll use recessive traits as an example.

If you've taken any biology in school, you should know what a recessive trait is. In essence, a recessive trait may not show up in generation after generation UNTIL two critters (dog, human, whatever

And glaucoma is just one of the genetic disorders for bassets.

I hope this makes some kind of sense. And I sincerely hope someone who can really explain it comes along!!

 

[Betsy Iole]

This question is currently the subject of sometimes vigorous debate within the fancy. When stripped of its emotional overtones, it's basically a debate about how best to use genetics and selective breeding to achieve specific goals, and the consequences, good and bad, of various approaches.

Here are some websites that outline the issues.

In-Breeding and other Breeding Methods
Inbreeding and Linebreeding
The Canine Diversity Project
The Price of Popularity: The Use of Popular Sires and Population Genetics
Canine Genetics Resources

Edited, after reading biscuit's post. She does a good job of outlining the basics. Mating of closely related individuals increases homozygosity, reduces genetic diversity, and fixes traits, both good and bad. This is how purebred breeds of today were developed.

OTOH, there is mounting evidence that preservation of genetic diversity is desirable for health reasons. Perhaps nowhere is this more important than at the MHC (Major Histocompatibility Complex) loci. The MHC plays a central role in immune function, and a high degree of genetic diversity is crucial to the long term survival of a population. For more information, see Practical medical importance of major histocompatibility genes in disease resistance and reproduction in dogs and Canine Autoimmune Disease: The Role of the Major Histocompatibility Complex .

[ February 23, 2004, 08:29 PM: Message edited by: Betsy Iole ]

 

[shallhb]

Sort of continuing this thread...I've never really understood dog breeding, and yes, I took high school genetics, but they kept talking about pink versus white sweet peas, or something like that, and I drifted off.
. Would it be likely to be linked to other (unhealthy) recessive genes, or what?
Sharon

 

[Dean]

Very simple-- my methods are called line breeding, - if you do the same, it's inbreeding !!

 

[biscuit]

Sharon, it's my understanding there's a strong genetic component for human behavior --- think of all those stories of twins separated at birth who meet 40 years later and have the same little bubble hairdo and mannerisms and are both wearing plaid shirts and cordovan loafers!

So, if there's a strong genetic component for human behavior, why shouldn't there be one for dogs?

 

[shallhb]

Biscuit,
Yup, I suspect that the traits that go into obedience are certainly in part inherited. There are three basset hounds in Northern California that show in obedience--two are from the same breeder, and the third is closely related to the other two.
What I was trying to say is--if there is a trait or set of traits that are uncommon in a breed, I'm assuming they reflect recessive genes (Come to think of it, maybe that's a wrong assumption--Huntington in human's is dominant and its rare ). Yikes, my ignorance is showing and I'm tangling this all up. Back to what I really wanted to know--would it be unhealthy to breed for a rare trait or set of traits, like an 'obedience' basset.
Betsy??

 

[Betsy Iole]

There's a belief in the breed that good fronts (front assemblies, not obedience fronts ) are "recessive", which I assume means hard to get and hard to keep. (Hmmm, maybe they mean obedience fronts, after all.) Anyway, just because they're regarded as recessive isn't a deterrent to breeding for them.

 

[Josey]

Thanks, it's clear as mud!
I wonder, after all that good information, if maybe Dean hasn't struck right at the heart of it?!
So, accepting the basic premise that modern "pure" breeds were developed by inbreeding, does this mean that a show breeder today is "responsible" because while s/he continues to inbreed dogs (as in, maybe one generation removed), s/he only choses dogs that have not demonstrated undesirable traits, such as glaucoma, certain behavioral or conformational characteristics? Does this, as with the glaucoma example, line us up for worse genetic problems down the road, as the more complex (and usually recessive so rare) abnormalities get closer and closer to a double-recessive combination?

 

[biscuit]

Hopefully someone will correct me if I'm wrong (which is kind of a given ) but ... I think, in order to avoid glaucoma and similar problems, you need to both refuse to breed pups known to have the disorder in their line AND do genetic testing.

Not all disorders express themselves, meaning not all disorders will actually show up in a line ... until that fateful day. Hey, it happened in my family even. A niece showed up with a rare ... I think it's called an autosomal homozygous recessive disorder. In other words, not a sign anywhere, but apparently my family and my sister's husband's family are carriers -

The same could happen with pups. Which is why the genetic testing is so crucial.

I think, if all parties are responsible, the likelihood of coming up with worse and worse disorders over time is kind of unlikely. I mean, how many generations back do bassets go?

The problem is ... the sheer number of irresponsible breeders. There's where the problems arise.

I think.

 

[pinehawk]

i've talked to to many field trial beaglers on this subject.line breeding can be the best way to preserve a bloodline,yet done wrong and some times with a outcross can screw up a life time of work.to some they consider inbreeding as brother to sister matings,some will bred father to daughter or mother to son and think that it's ok and in some cases it is but the next breeding for those pups should be a little on the outcross side,some still consider this to too be inbreeding.but most seem to like to get no closer than aunt to nephew or uncle to niece.no matter what way you breed you have to be prepared to cull dogs.

 

[Mikey T]

"I think it's called an autosomal homozygous recessive disorder. In other words, not a sign anywhere, but apparently my family and my sister's husband's family are carriers -"

THere are next to nil actual DNA tests for genetic disorders but more are coming all the time. The most common an effect method currently is a comprehensive screening of the breeding pairs history(pedigree) and the history of the offspring of those dogs in it. An autosomal homozygous recessive disorder is can go unnoticed even in a good breeding program. and then again in Doberman Pinchers such as disease afflects 35%
of the dogs and when including carriers the numbers climb to >70%


"After doing obedience with a basset and enjoying it alot, I've wondered, could someone breed a healthy line of bassets that liked obedience (i. e., could be trained to give the handler attention)? I assume it's a recessive trait , since it doesn't seem to be characeristics of the breed ."

The very purpose of the breed was to hunt rabbit with little or no input from man. This is directly contrary to formal obedience to breed for obideince bidability would destroy the vary essence of what a basset is. While it may not be a health use it would still destroy the fuction of the dog.

"you need to both refuse to breed pups known to have the disorder in their line AND do genetic testing."

while a noble concept it is often not practical. In doberman's upwards of more than 75% of the dogs are either carriers or afflicted with Von Wilbrands desease a bleeding disorder that also effects bassets. This has been traced back to the use a frequent sire. With such a large precentage of dogs as carrier or afflicted eliminating them from a breeding program would create even less genetic diversity while eliminating the disease. So for the time being and the % of clear dogs increases, the recommendation is to not breed afflected dogs and only breed carriers to clear dogs. This eliminates afflicted dogs and increases the ratio of carriers to clears to 50% or less.
Second if there is a DNA test for a disease there is proof of whether a dog is clear or not regardless of its line history. There is no scientific basis not to breed a geneticly tested clear dog even though there is a history of the disease in the line. DNA genetic testing supercedes any historical basis for evaluating predalection for a genetic disease. There are very few Genetic test available. FWIW the gene resposible for vWD in dobermans is not the same as in Bassets so the at present there is no Genetic Test for vWD in bassets but they are working on it. There is a test, though not as acurate a gentic testing, that can provide insight into whether a dog is clear, a carrier or afflected.

links
Popular Sire Syndrome and Concerns of Genetic Diversity

The Doberman Pincher breed has a problem with von Willebrand’s disease; an autosomal recessive bleeding disorder.  Genetic testing has found that the defective gene is present in 77 percent of Dobermans.  Doberman breeders can test and identify carrier and affected dogs.  They can decrease the defective gene’s frequency by breeding carriers to normal-testing dogs and selecting quality, normal-testing offspring for breeding.  By not just eliminating carriers, but replacing them with their normal-testing offspring, genetic diversity will be preserved.  

The perceived problem of a limited gene pool has caused some breeders to discourage linebreeding and promote outbreeding in an attempt to protect genetic diversity.  However, it is a fallacy that each dog must carry the diversity of the breed.  Studies in genetic conservation and rare breeds have shown that this practice actually contributes to the loss of genetic diversity.

SELECTING FOR VIGOR

DNA Studies in Doberman von Willebrand's Disease

What should a breeder do with the test results, once they are obtained, in terms of breeding decisions? The problem facing the Doberman breeder is that it appears that only 15 to 20% of Dobermans are clear of the vWD gene. If one breeds mostly clear to clear, it narrows the breeding pool so much that there is risk of losing some of the Doberman's genetic heritage, i.e., some of the genes determining valuable positive characteristics of the Doberman might be lost, or highly diluted. Therefore, as a first priority, we advise breeding clear to clear and clear to carrier, at least for the next two or three generations. Over time, as the frequency of clear dogs increases, it should be possible to breed mostly clear to clear, and to eventually eliminate the mutant vWD gene.

Correlation of DNA test with factor assay

Basset Hounds Needed for von Willebrand’s Disease Research
for VetGen’s DNA Test
"VetGen has developed direct DNA tests for nine different dog breeds, for three different mutations of von Willebrand’s Disease. There is not yet a test for von Willebrand’s Disease in Basset Hounds, but VetGen would like to try to develop one."

 

[Guest]

On Feb 23rd, S. Hall wrote:

would it be unhealthy to breed for a rare trait or set of traits, like an 'obedience' basset

I'm pretty sure I had the same pink and white peas in my high school biology class. However, despite my lack of credentials, I don't mind expressing an opinion. I don't think its possible to breed a good basset that likes obedience and wants to pay attention. A healthy basset, perhaps, but not a good one. In order to breed in that kind of work ethic, we'd have to breed out all the independent, "what's in it for me" spirit we love. What we'd end up with would be a Border Collie that drools a lot.

Now, what would be a REALLY interesting to study is not so much the inherited characteristics of a group of "obedience" bassets, but what it is that makes their trainers tick .

 

[biscuit]

only breed carriers to clear dogs. This eliminates afflicted dogs and increases the ratio of carriers to clears to 50% or less.

Yes. I think.

 

[Betsy Iole]

Here's the link to interpretation and breeding strategies based on results of DNA testing for simple autosomal recessive disorders. It's in table form, and it's very straightforward.

Interpreting Your DNA Test Results for Autosomal Recessive Diseases and Breeding Strategies

[ February 25, 2004, 10:35 AM: Message edited by: Betsy Iole ]

 

[shallhb]

A border collie that drools alot? Or a very short dog that stares at you intensely 24 hours a day?
I think the definitive genetic study has not yet been done on people that do obedience training with bassets, but after class last night (where my little charmer sniffed her way up to the high jump, then hurtled herself over to get the dumbbell), the genotype will probably be a mix of two genes, one that expresses itself as 'quite nuts', the second as 'almost impossible to humiliate publically'.

 

[Betsy Iole]

I nominate the "more determined than your basset" gene as a candidate for screening.

[ February 25, 2004, 10:56 AM: Message edited by: Betsy Iole ]

 

[Josey]

As I sit here thinking of inbreeding, and the concept of those really bizarre, rare recessives that will show up "one fateful day, I can't help of thinking about two things:
1. An excellent novel called "Middlesex," tracking three generations of inbreeding within a human family -- narrated by a hermaphrodite in the third generation, and
2. Trudy, my friend's (pet-store purchased) German shorthaired pointer, who is also a hermaphrodite. Not an inexpensive (nor comfortable for the dog, I would think) operation to fix the aesthetically disturbing outward signs of Trudy's condition.

I've been working my way through the excellent links Betsy provided (not all the way through yet, so pardon my current state of ignorance), but it seems like shopping for sires from other reputable breeders, rather than continuing to line breed one's own dogs, on a regular basis would thin each breeder's gene pool in a good way.
I'm sure I'm oversimplifying here, but are people reluctant to do that because outside dogs represent greater unknowns than those within their own programs? Is it just ego -- I want to breed the best basset ever, and I want it to come exclusively from my lines? Something else?

 

[biscuit]

OTOH, there is mounting evidence that preservation of genetic diversity is desirable for health reasons.    

Yes. I didn't want to get into that because it seemed to complicate the debate. But I had to do a lot of studying of it in biological anthropology coursework.

Sickle cell anemia is the classic example --- I believe it's another autosomal homozygous recessive --- I know for certain it's recessive.

It also developed in populations where malaria was prevalent. And it appears to act as a fairly efficient protective mechanism against malaria for carriers of sickle cell. So it was selected for.

[ February 25, 2004, 05:02 PM: Message edited by: biscuit ]

 

[Betsy Iole]

(Disclaimer: I'm not a breeder, so I can only write about my observations.)

it seems like shopping for sires from other reputable breeders, rather than continuing to line breed one's own dogs, on a regular basis would thin each breeder's gene pool in a good way.

Most reputable basset breeders, with the exception of a handful of larger kennels, keep only one stud dog at a time, but they generally keep and breed several bitches during a given interval. They almost never breed all their bitches to their single stud dog; this type of practice, in my experience, is more typical of a BYB or commercial breeder. Instead, their stud dog is used by other breeders, and they use other breeders' stud dogs, as you mentioned. These breeders may have lines that are related to a greater or lesser degree, but not always. In my dozen or so years in the breed, some of the biggest winners have been outcrosses.

If you can stomach it , here's another link, an Introduction to Population Genetics. Although it talks about the importance of heterozygosity (diversity) it also includes the following section.

Out-breeding Depression

In some cases, inbreeding is purposely done to create a \"pure line\" of individuals which all have similar genes. This is the case with many domesticated species such as pure-bred pets, laboratory animals, and agricultural plants and animals. Breeders intentionally inbreed to create a population that has the genes for desired traits in a homozygous state, so that the offspring will perpetuate the desired phenotype. Over generations, individuals with deleterious genes are removed from the breeding population, resulting in a monomorphic, yet healthy population. These populations can actually suffer \"out-breeding depression\" when crossed to unrelated individuals which results in new combinations of alleles, and possible entry of deleterious genes.

Inbreeding or \"line-breeding\" as it is referred to by pet breeders, must be done very carefully to prevent the creation of a line that is almost perfect but contains a major flaw, such as domestic dog breeds that have the propensity for hearing problems (Dalmatians, cocker spaniels) or seizures (Irish setters). Responsible breeders will often discontinue breeding a line whenever the slightest chance of a deleterious gene is noticed, sacrificing many years of work to prevent damaging the breed.

When I said this was the topic of debate, I was guilty of understatement. I've read several flame wars between proponents of line-breeding and proponents of assortive mating, and if I were to start breeding I'd probably incorporate both practices into my program, depending on my goals for a specific breeding.

However, this may actually be something of a moot discussion...a preliminary investigation finds that numbers of MHC alleles, while quite numerous and varied between breeds, are relatively limited within breeds. We may be trying to close the barn door after the horse has escaped.

Kennedy LJ, Barnes A, Happ GM, Quinnell RJ, Bennett D, Angles JM, Day MJ, Carmichael N, Innes JF, Isherwood D, Carter SD, Thomson W, Ollier WE. Extensive interbreed, but minimal intrabreed, variation of DLA class II alleles and haplotypes in dogs.Tissue Antigens. 2002 Mar;59(3):194-204.

An interesting speculation in the above abstract:

The high interbreed, and relatively low intrabreed, variation of MHC alleles and haplotypes found in this study could provide an explanation for reports of interbreed variation of immune responses to vaccines, viruses and other infections.