Cardiomyopathy in Boxers being a prime case . it has been traced back to US imports, and is now rife in the breed!

Line breeding is misunderstood by most dog owners. All my dogs are line bred to some degree, my Border Collies all are & it has been used to keep the traits that are needed & to bring in any that are "lacking"

For example my Rjj is Keewee's half brother, Rjj is way too strong for obedience & very much a hill dog like the very strong hill dogs he is line bred to in his pedigree. Keewee on the other hand is line bred on her father's side to dogs who are strong, but exceptionally "biddable"& basically a much more all round dog. Good for herding & anything else they are wanted for.

Many people mistake line breeding to in breeding/close breeding.

To breed living thing let alone dogs, one should have an indepth knowledge of what is behind the parents to be & also what can be produced from such a mating.

It's funny but Isla's breeder once said that out crossing always made her a little nervous as unlike line breeding, she is never 100% sure what is behind other lines, but did it because it was necessary to keep the lines healthy.

I think that sums up my opinion really. Line breeding has it's place and isn't particularly unhealthy as long as it's used correctly and only really by those who know what they're doing.

I did'nt post this on another forum, just responded to an on going thread. will check later for new replies on there.

Sorry hun, my mistake, but it's made for interesting reading, funny how people view what is really seen as a common breeeding practise, and not just for dogs by any stretch of the imagination.

Intresting indeed, just caught up. well them posts shut a few up

Yes I think they did, I can't believe sometimes just how rude people can be though, about something they obviously know very little about.

Yes, does'nt make you want to help them ah?

'Breeders that line breed are being lazy'.

I must admit, I bit my tongue at that post, I really did want to comment but thought as others had already made the point very well, it wasn't worth it. From the tone, they were just trolling for a response in any case.

As I understand it (though I'm no expert) the advantage (and skill) of the line breeder is to maintain/concentate or balance certain characteristics in the off-spring. And people are right to comment that pretty much all dogs have 'line-breeding' (including crosses as their parents will have bee line-bred).

Some confusion lies around the term 'line-breeding' v 'in-breeding' - they are not so distinct as people would like to believe. Although line-breeding implies relationships are not so close, where sires have been over-used, and/or the overall population of the breed is small, the genetic similarity is such that the off-spring are essentially 'in-bred'. This has been studied in dogs, finding high levels of 'in-bred' dogs even in populations of 1000s where breeders have not been deliberately 'in-breeding' in the usual sense.

The other issue which gets conflated with in/line-breeding is that of breeding for particular and excessive features which have caused well-known defects and health issues in some breeds. I, and I would think most of the public find it sad, for example, to see a breeder saying that she needs to know that a potential puppy buyer is well-off as her breed is prone to (expensive to fix) eye problems, or reading about breeds of dogs where it is standard to deliver puppies by c-section. However, whilst this has been achieved by selecting and in-breeding stock for a certain 'look' it is demonstrably different to, say, breeders of working BCs where the health of the parents will have been a key factor.

'Myth' of the healthy cross-breed does make sense based on genetic studies. If health issues are often caused via inheritance of two deleterious recessives, logic says that greater genetic variance is likely to produce a healthier dog, environmental factors being equal. However, given the relatively recent existence of many of today's breeds, it also means that dogs from different breeds, may, genetically be relatively similar which may diminish the success of the out-cross. This is no different from humans in the sense that we are a relatively recent species and a caucasian human shares a great deal of genetic material with another caucasian - one reason why in different races, different diseases tend to prevail whilst others are almost unknown.

So line-breeding as such is not necessarily a terrible thing in itself, anymore than someone that marries their first cousin will have unhealthy off-spring. The issue comes when the same 'lines' dominate and are chosen again and again so essentially the 'effective population size' is diminished.