Line Breeding in Dogs - read this before buying a pedigree puppy!

What is line breeding in dogs and why should you care if the puppy you are thinking of adding to your family has been line bred?

 
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The next question was sent in by Paul, and he says that a friend of his was interested in a dog, but he's concerned as it is line bred. What are your thoughts on this practice? He's just done some reading up on it and actually as an addition, this dog is a result of a father-daughter breeding.

So to start with, line breeding is not something that I've really knowingly come across in practice in the areas where I've worked. Line breeding is something that involves breeding from related to dogs in the same family. I don't feel that that would be something really to be encouraged, and I'd really caution as to the potential long-term health of an individual bred in such a way.

Inbreeding in pedigree dogs

If we think of dog breeding in general, it's produced so many problems through the narrowing of the gene pool to try and select for desired traits and the result has actually been that while we may have achieved those desired traits, generally they're in the looks of the dog, they often come with a lot of problems attached.

What is line breeding?

We just have to think of Westies with skin disease, Pugs with breathing and spinal issues, Labs with hip dysplasia, Cavalier King Charles with their heart disease and the list goes. Line breeding is a way to try and take the isolation of a specific characteristic to another level. So you're saying you've got this dog that either looks a specific way or behaves a specific way and you're trying to really breed within that line to accentuate those characteristics even more.

Is line breeding always a bad thing?

Having said that it’s a bad thing, actually the level of inbreeding that's going on with line breeding does vary an awful lot. So it could be that the parents of the puppies are actually third cousins and if that was the case then the risk to the individual of developing any problems and serious consequences of inbreeding is actually going to be very low. It's probably not even going to be over and above the normal breed risks. So that wouldn't be something to worry about and actually, if it's known that the dogs in the line are all healthy and they’re all much better than the normal levels experienced within that breed, then a result of a line mating from such distant relatives is actually much more likely to result in a healthier dog.

An example would be if you've got a line of Westies and none of those have ever had atopic dermatitis, they haven't developed itchy skin, then actually it could be really desirable to line breed from those dogs, but making sure that the parents are really distantly related, not father-daughter related.

The risk of health problems

We can actually calculate the risks or the probability of problems developing, and that’s by calculating something called the coefficient of inbreeding. This figure essentially tells us how likely it is that the puppies will inherit identical genes. Too high a number and we see health problems, we see a loss of vitality, we see poor growth. However, if that coefficient of inbreeding is very low, then we're less likely to get the desired benefits but their health won't suffer either.

So really a healthy figure to aim for is a value of less than 5%. In simple cases, parent-offspring mating’s have a coefficient of inbreeding of 25%, siblings bred together have a level of 25% as well. Even first cousins have a coefficient of inbreeding of 6.25%. Those levels are all significantly higher than that 5% cut-off and we definitely don't want to consider this.

So in this question, that father-daughter mating would give a coefficient of inbreeding of at least 25%. However, when lines are already inbred, and they are already significantly inbred, then the values can actually be much higher. Even if at first glance the parents seem to be only distantly related. It can become a very complicated calculation but there are ways of working that out and a good breeder should definitely be considering this when they are line breeding.

Father-daughter mating?

As for father-daughter breeding in any situation, that's not something that I would recommend. I don't think it's a good idea. I think the risks are significant of having puppies that have compromised health. It's not going to be every puppy, but there's definitely that risk and we shouldn't be producing puppies that have a high risk of health problems in any situation. But father-daughter mating in this situation, I'd really be steering well clear of.


The above is a transcript taken from “The Dr Alex Answers Show”.

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