Inbreeding- some research.

Becs · Posted: Sat Aug 30, 2008 12:06 am Post subject: Inbreeding- some research.

Whilst sitting up with sick dogs in the small wee hours tonight, I've been reading the Cold Wet Nose blog by Beverley Cuddy who is the editor of Dogs Today Magazine and was interviewed on the Pedigree Dogs Exposed Documentary.

She has included some research done by Professor David Balding and there is a very good summary of it by someone called Terrierman (I think its a Blog-name?)

I'm not sure if its allowed to copy and paste it onto LF, but I'm sure I'll be put right if its not the done thing - appologies in advance if it's not OK - I just think it makes interesting but alarming reading and would be interested what other more knowledgable people make of it.

Becs and The Gang

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The study is based on a 10-breed sample of 2.1 million dogs in the Kennel Club's electronic pedigree data base. The Kennel Club's database contained records of a total of 5.7 million dogs from 207 breeds as of the end of 2006. The Kennel Club's electronic data base was begun in 1970.

This is the first systematic attempt to study Kennel Club population structure using The Kennel Club's own pedigree database.

The 10 breeds examined were: the Rough Collie, the Golden Retriever, the Boxer, the English Bulldog, the Chow Chow, the Greyhound, the German Shepherd Dog, the Labrador Retriever, the English Springer Spaniel, and the Akita Inu.

The researchers note that inbreeding condenses and exacerbates genetic disorders with a population:

"Dog breeds are required to conform to a breed standard, the pursuit of which often involves intensive inbreeding .... This has adverse consequences in terms of loss of genetic variability and high prevalence of recessive genetic disorders. These features make purebred dogs attractive for the study of genetic disorders, but raise concerns about canine welfare."

The researchers note that many dog breeds are associated with specific genetic disorders that have been magnified by inbreeding:

"Many diseases affecting dogs have high prevalence in one or a few breeds, such as Addison’s disease, common in Portuguese Water Dogs (Chase et al., 2006), interstitial lung disease in West Highland White terriers (Norris et al., 2005), and dermoid sinus in Ridgeback dogs (Salmon Hillbertz et al., 2007)."

The authors found disturbingly high levels of inbreeding within most Kennel Club breeds they looked at:

"We find extremely inbred dogs in each breed except the Greyhound, and estimate an inbreeding effective population size between 40 and 80 for all but two breeds. For all but three breeds, more than 90% of unique genetic variants are lost over six generations, indicating a dramatic effect of reeding patterns on genetic diversity."

The number of generations studied ranged by breed from 5.9 in Greyhounds to 9.0 in the German Shepherds, with an average over the ten breeds of 8.0 generations of dogs analyzed.

Popular sires are part of the problem, but not all of the problem.

"Popular sires (defined here as > 100 recorded offspring) are evident in all breeds except Greyhound. Golden Retrievers have the largest proportion of popular sires (10%), and conversely the lowest proportion (5%) of male dogs that are sires. . . . Highly-prolific dams (> 40 offspring) are concentrated in three breeds: German Shepherd, Golden Retriever and Labrador Retriever. Most dams have just one litter recorded."

A closed registry system is the core of the problem.

"Dog registration rules have only been rigidly enforced for about 50 years, prior to that occasional outcrossing was still possible."

The Kennel Club needs to change the way it does business

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_Jules_ · Posted: Sat Aug 30, 2008 6:56 am Post subject:

Very interesting Becs.

I always knew that Greyhounds were a revoltingly healthy breed on the whole, but I hadn't realised why. I do wonder if there is a difference in the general health between the Racing Greyhound and the Show ones though, as the show types are obviously bred specifically for the ring, so breeders use only the dogs which match the breed standard most closely. Confused

sue51 · Posted: Sat Aug 30, 2008 7:23 am Post subject:

Interesting reading Becs - BUT, I would be interested to see much more specific information from the research.

My database calculates the inbreeding Co-efficient over the number of generations required (up to 50) if you search the web, you will find that the person responsible for that programme openly admits they do not understand the inbreeding COI's and how they are calculated - there for anyone who cares to read.

Diana · Posted: Sat Aug 30, 2008 7:31 am Post subject:

So becs why do you find this alarming? Linebreeding has been used for every generation since the start of time.

The only entirely unlinebred dogs are mongrels and crosses. And owning those are not to everyones taste.

There are many many healthy pedigree dogs out there, all that will be linebred to some degree if you go far enough back, and many who are linebred quite tightly (take Ida for example....)

And beveley Cuddy is a dreadful woman given to distorting anything if it sells her magazine or agrees with her wierd and prejudiced, against the show world and breeders, point of view. Having had a run in personally with her I can tell you she doesn't bother with facts much.

Di

sue51 · Posted: Sat Aug 30, 2008 7:36 am Post subject:

AngelaC · Posted: Sat Aug 30, 2008 7:54 am Post subject: Re: Inbreeding- some research.

Interesting info about the show type greyhounds. Within the racing industry I gather there are dogs that have sired thousands of dogs and sadly bone cancer seems to be rather prevalent.

JohnW · Posted: Sat Aug 30, 2008 1:56 pm Post subject:

I think the info probably came from this study Becs:-

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2390636

Regards, John

Becs · Posted: Tue Sep 02, 2008 5:53 pm Post subject:

JohnW · Posted: Tue Sep 02, 2008 7:00 pm Post subject:

The article was actually being used as a model for human genetic desease Becs. (Department of Epidemiology and Public Health, Imperial College, London)

By it's nature, any pedigree breed for any animal, be it Pig, Cat or Dog, must have a closed registry system. Although I dispute the statement "Dog registration rules have only been rigidly enforced for about 50 years" I clearly remember when Labradors moved from being a "Variety of Retriever" to being a breed in their own right and am sure it is nearer to 40 years. But in all honesty, thats only a matter of degrees.

There have been several times during the history of the breed when the gene pool has become very bottle necked. The reasons for this are varied. Possibly the biggest bottle neck was at the time of Ruler of Blaircourt and the great Sandylands "T's", Tweed, Tan and Tandy. By todays standard these dogs did not produce anything like as many pups as can happen today, but in those days the gene pool was so much smaller, so percentagewise the effects were vast. Possibly more worrying is the bottle neck behind chocolates! Behind just about all modern chocolates are the same two dogs. Follytower Merrybrook Black Stormer and Morningtown Toblar. I also worry about what bottle neck we will find at the back of fox reds. You breeders have that one in your hands, so please be very careful. Looking at working lines we had a big bottle neck at the time of Pocklea Remus. Some people were a little worried about how this could adversely affect the breed which was one of the reason Aughacasla Sam of Drakeshead was brought in. Sam was very very good and himself became a bottle neck almost as big as the bottle neck he was brought in to counter. But Sam was also the first bottle neck which also brought in a major problem, GPRA!

But we have been lucky. Sam brought a problem into the breed just at the time when Optigen brought in the answer to the problem. Will we be so lucky the next time? Is following "Flavour of the month" clever?

As some of you know, I have an interest in Flatcoats and have a "Very" small database of the. Do you know, there was only three lines without Sharglean Blackcap in it. Sadly my friends line is no more so now there are only two. There are a lot less Flatcoats around so chase the champion was always more likely to bring that result than in Labradors, but it could happen!

Regards, John

velvetine · Posted: Tue Sep 02, 2008 7:38 pm Post subject:

some-one said a rather interesting thing to me the other day about Linebreeding.....................

bare with me folks

ok my family name is Stuart and the chap round the corners family name is also Stuart.................................as has the woman in the next village

now that DOES NOT make us related, we only share the same name

now I know that if you go back a long long time there is every chance that we are all related, well we did all come from Adam and Eve after all

sorry to lighten the mood slightly but it is true just coz a dog has the same kennel name does not always mean that it is a direct relative

hope you can understand my ramblings Wink