totally agree with ecini, and i love mongrels, i think too many breeders that linebreed / inbreed do it to get the looks and dont give a stuff about health

As a breeder who hip scores, eye tests and now kidney function tests her breeding stock in a breed with over 20% of all registered stock in a numerically small breed being tested and bred to a stringent code of ethics I object to that statement.

My breed is well known for it's good temperaments and robust health and careful line breeding as well as expensive importing or travel to foreign studs helps keep it that way.

I am contemplating a tight line breeding mating two offspring of my older champion bitch.

Her champion daughter (who is to be the Mum) has an imported sire from the USA who is totally unrelated to the imported sire (Norway) of the young male. The bitch has already produced a healthy good natured outcrossed litter to an unrelated (except maybe right back) dog with mixed results re the type I wanted (not reproducing either parents qualities reliably, but overall nice litter). Unfortunately there were only two bitch pups in the litter and I didn't get the quality I wanted in the one I kept, though her sister has turned out well.

Their Mother is the type I want to breed, and has a wonderful temperament which she has passed on to her 18 healthy offspring from her 3 litters (two by same sire).

Also importantly she has produced quality in her litters, and I do not want to risk loosing her traits by more outcrossing again.

Also I will obviously know my bitches pedigree very well as she is my Fourth home-bred generation and she has many healthy typical relatives.

All my dogs will also soon be able to have a newly developed DNA test for the low incidence late onset PRA that has cropped up from time to time in the breed (very low considering line breeding is inevitable in a small population).

The health genetic health of breeds is influenced greatly by the care an knowledge of the breeders. Where the breeders are knowledgeable and caring the incidence of problems is kept limited by whatever means are available, in other breeds with large numbers of Fly by night puppy producers improvement/maintenance of health and temperament (not to mention type) is constantly hampered by such poor breeding.

I suppose if I was looking at a litter that was closely bred I would ask the breeder why they made that choice and would expect an answer something like the above (a good thought out reason, not just because they could or the parents were handy).

i didnt intend to offend ethical breeders, but i still am entitled to have an opinion. and if the breed has a very small gene pool are breeders making the gene pool even smaller by close linebreeding (inbreeding) to get the line (look) they want.
you know your dogs are healthy, and know the health issues in the breed, but i still stand by my opinion that health should come before looks, but at shows dogs are only judged on type (looks).

Of course your entitled to your opinion, but sweeping generalisations can be challenged.

Even in breeds with known hereditary problems the vast majority of carefully bred pups will be healthy, that cannot be said about a lot of the randomly bred ones, not even the crossbreeds if the stock they come from is unhealthy. Poor temperament though is just as likely whatever the looks.

Show dogs are not only judged on looks (though these are the most obvious traits), they should exhibit typical temperament and be sound. A dog that is deaf or blind is subject to disqualification, and also dogs that have had operations that alter their natural conformation, other than neutering and certain accidents are also not allowed to be shown.

In order to have a breed you have to have common traits.

You can with care have small populations that remain healthy by strict selection of breeding stock. We have it with Park cattle and with the ponies already mentioned. Selection can be natural or artificial. Natural is more ruthless, but modern selection with health screening is pretty good alternative to random matings which would still require selection to be healthy.

Left to nature all dogs would be medium size brown, and prick eared with a sabre or curling tail, google pariah dogs.

A dog is not a natural Beastie at all, but a man made creation to suit mans needs for a helper, to hunt, herd and protect. Companionship can be had from any of the dogs whatever their original purpose.

I really do hate stepping into these arguments, but from a purely veterinary point of view, restricting the genetic diversity is *never* healthy.

you can test for all we know about, but no-one has yet devised tests for all the deficiencies in immunity that arise as a result of close line-breeding (aka incest) and while there may well be environmental issues (vaccination, feeding, infra-red microwaves, mobile phones - who knows?), genetics must play a huge, huge part.

And there will always be new inherited diseases we haven't found yet. By checking for those we have, you are being partially responsible, but there is no such thing as responsible line-breeding. It's an oxymoron. And type doesn't matter when you look at the larger picture of canine health.
There was an amazing article in New Scientist on the perils of losing genetic diversity in a small population - I'll try to find it and post the link.

sorry, but it just can't be done.

Eceni

I assume you would both like to see purebred dogs phased out in favour of a generic dog, but which characteristics would you breed out,a nd which in?

Many of our beloved characteristics are not the ones that would best suit a wild Canid, and many of those that suit a wild Canid are totally unsuitable for the domestic dog.

Should the Domestic breed become a babified small floppy eared lapdog, or be allowed to revert to a suspicious natural prick eared predator?

As you prefer mongrels, how would you have these be bred and selected, as it is fairly accepted that the majority of such dogs are the product of some persons lack of responsibility.

Health or otherwise is purely chance, maybe some are pretty healthy as they had a hard start and the weaker ones never survived.

Health aside, what about temperament.

Our domestic dogs have a very wide range of mental characteristics that either endear them or totally turn people off them.

For example I enjoy living with my self sufficient affectionate breed but could not bear to spend time with some others, especially over clingy floppy eared drooly ones.

Your ideal dog is probably poles apart from mine and mine poles apart from someone else's.

The domestic dog has the widest variation in all domestic species, why is that?

It's because dogs live in closest association with homo sapiens, a species which has so completely lost the plot that it will create everything from the English Bulldog to the Sharpei and not see that each of these is a genetic catastrophe.

In the middle, as you say, is some wide variation - but would it not be possible to out-cross within breeds, and yes, even to open the stud books so that, say to take a breed at random, Border Collies could be improved with Working Sheepdog blood without losing the phenotype that makes them Border Collies? And begin to treat health as if it were as important as, say, 'type', when type is a completely arbitrary thing, that changes over the years (see the changes in skull morphology for the St Bernard published in the current issue of Your Dog - I think - or it might have been Dogs Today - and health is not arbitrary at all?

If you line breed, you *will* create inherited defects. It's all a question of time.

sorry

E

You can't create an inherited defect, only bring it to the surface.

In actual fact when bringing in new blood you may inadvertently bring in something undesirable which you don't know about until it is spread into the gene pool and sooner or later two animals with the same negative gene produce an affected animal.

Better to practise line breeding with any new bloodline to test for it's positive influence first, before disseminating it in the breed as a whole.

Many negative traits have appeared in a breed as a result of an outcross.

Any breeding system has to rely on selection.

There is only one certainty in genetics, constant change.

Wild species are continuing to change and evolve.

For example African Elephants are more frequently being born that only grow small tusks, and some with none, as those with the genes for large ones have been hunted out.

Nature plays constant games to see what will work.

Man tends to not inbreed, but has a multitude of genetic disorders.

Some of the worst ones still appear in countries with a high infant mortality rate.

Some disease genes have proliferated because they had a positive effect on survival. One such is the sickle cell trait which increases resistance to malaria.

Our dog breeds may end up with weak traits that would stop them surviving in the wild, but the majority of breeds are fairly healthy, my own is not so far from the original template and unlike many breeds has changed very little other than perhaps shade of coat fashionable at any time.

If it wasn't for the advances in Veterinary medicine I am sure most Bulldogs, Bostons etc would still be self whelping. So are the Vets to blame?

More breeders in the US are using AI routinely, and what have they found that they have dogs and bitches lacking natural breeding behaviour.

In a way though most of these problems will be self limiting.

If people do not select sensibly against truly debilitating health issues and also general thrifitiness then their breeds will die out. Fertility will fall, and no-one will want to own them if their health is so poor.

In Laboratories mice are inbred for many generations before serious problems emerge, so the occasional use of judicious line breeding, allied with stringent selection is still valid if one wants to breed livestock with uniform and predicable traits.

This is important for meat production, for performance, and for type.

I certainly do not advocate constant tight breeding, but going back into ones lines to consolidate things after several outcrosses is the way not to loose what you have striven to gain.

Because my breed ahs a small gene pool in this country we have to bring in new blood almost every other generation, and we have problems stablising type as a result, because we do avoid excessive inbreeding.

I agree with the bulk of what you're saying - which is that with stringent culling, line breeding can work. Somewhere at hte head of this thread is my example of the Icelandic Horse where there's a small, closed gene pool, but very harsh natural selection and the population has survived - tho interestingly when you bring them out of Iceland, they have a very high incidence of sweet itch - an allergy to midges... its seems that the immune system can become very fragile in the presence of reduced genetic diversity.

But in our dog breeds, that culling doesn't happen. DOgs may, eventually, be removed from the gene pool if they have serious over disease, but most often they simply get passed on to pet owners who have to deal with the catastrophes that result.

this is the URL for a list that details the noted inherited diseases in dogs: http://www.nzymes.com/Articles/hered...s.htm#Section1


I have no idea if your breed is listed, but what I have discovered is that while some of these have a very low incidence (they're not trying to pretend they're all at epidemic proportions) the list does not by any means cover all the bases. If your breed isn't there, it's not because it doesn't need to be, it's just the measurements haven't been made.

so - in-breeding, by definition, reduces genetic diversity. You're right that it doesn't create disease per se, but it does bring it to the fore and not only in the overt diseases like HD and PRA, the general weakness is not necessarily noticeable by the average dog owner. even the overt cases - bulldogs who cannot give birth except by caesarian surgery being the obvious example - are not considered abnormal by their breeders. So suggesting that problems are self-limiting, sadly appears not to be the case. Turkeys haven't been able to breed naturally for years, but it hasn't stopped the reproduction of turkeys.

And lab mice have been very, very heavily culled to produce some strains which are pretty much clones. If you're trying to get to a dog which reproduces entirely itself - where every gene homozygous, then please do carry on - but know that you'll have to cull mercilessly and I would ask why anyone would do that?

and people do in-breed, sorry, ask any medic.... it's one of the big, big elephants in the living room that they're all afraid to mention aloud, but scarily present.

Good to have a sane conversation about it, tho'

As said limited inbreeding is needed to maintain a breed as a breed. any race or sub species is one because it's genes are more like than unalike compare to other races sub species.

linebreeding is a useful tool that should be e used sparingly, in conjunction with careful selection. outcrossing is only useful if used in the same way, no point in it if it does not achieve your goals of health type and temperament, each being equally important.

As for the self limiting, there are still people prepared to breed animals that can't reproduce naturally, but just as many who are not prepared to own or breed such.

I have to commend the various Kennel clubs who actively are trying to discourage extremes.

Breed standards have been altered to change emphasis and the faults paragraph has been changed to:
Faults
Any departure from the foregoing points should be considered a fault and the seriousness with which the fault should be regarded should be in exact proportion to its degree and its effect upon the health and welfare of the dog.

It is up to breeders to select against the over exaggeration (will take time) and of course judges must penalise it. No breeder or exhibitor wants to breed or show dogs that will consistently get low placings.

Sadly though in popular breeds so many pups are bred without any care to health, temperament and breed standard.

I find it sad that the Veterinaroy proffesion at general practice level to not seem to know or advise potential breeders to avail themselves of health testing schemes.

None of my local Vets for example coudl get me the list of Eye panelists, and I had to trawl the internet for myself.