Sorry! Just accidentally deleted the KC linebreeding thread

Apologies to Pat in particular who had just posted a question to a duplicate thread. I merged the two threads and was deleting the duplicate post but as it was the first post in the entire thread, I accidentally lost the whole thread. :sl*p:

For those who were following the thread, it related to the fact the despite at first denying that the issue was a problem or a concern, the KC has now formally banned close line-breeding and made a number of other announcements about new approaches to breed standards for selected breeds.

http://www.thekennelclub.org.uk/item/2234/23/5/3

Ryan O'Meara:

http://www.dogmagazine.net/archives/1702/kennel-club-bans-father-to-daughter-matings-finally/

Sorry to those of you who had made further posts.

Pat had asked any experienced breeders whether close linebreeding is always a problem, having had several long-lived dogs from linebred lines.

You scared me as I thought I did something wrong!

After many instances of taking a long time to compose a post and losing it, I have a habit of saving posts in a word doc, so below is what I wrote. FWIW, I'm generally terrified of dogs with high COI's and I try to avoid having them. These were just some thoughts and I'm wondering what folks think:

I'm curious about this as I read comments by several breeders in Dog World that "breeders don't do close breedings (mother/son, brother/sister) anymore."

I happen to own a 6 year old Cavalier bred by a well-known UK breeder who is the result of a breeding of a dog to his dam's full litter sister. I presume that this is darn close to a mother/son breeding, but perhaps I am mistaken (different mix of genes among littermates). (For many personal reasons, this dog will remain anonymous.) He is a retired show dog and is absolutely lovely with a perfect temperament. He also happens to be heart clear at 6, has no outward symptoms of SM, and has no other health problems at this time. My question - is this considered a close breeding - one that "isn't done by responsible breeders"? Had I seen the pedigree before I took him, I likely would have been reluctant to take him. On the other hand, since he came to me at age 4, I felt pretty comfortable taking him since I had a good idea that he had no severe health problems as he was approaching middle age. Had he been a puppy, I think I would have not taken him. (Which is the main reason at this point that I only acquire middle aged Cavaliers in an attempt to have fewer health surprises.)

Further regarding line breeding, I have had five Cavaliers from Liz Spalding (Kilspindie), an early U.S. breeder who was well known for close line breeding. Those five lived to be 16 1/2, 16, 13, 14 1/2, and the last living one is currently 13 1/2 and is also heart clear. Cause of death for two was cancer (16 and 14 1/2); HGE for the 13 year old, and the 16 1/2 year old was euthanized due to quality of life issues (senile/blind/deaf). The majority of Kilspindies were known to be long-living. On the other hand, the two oldest of those were the result of an outcross with a Homerbrent bitch, and there was an outcross with a Sukev bitch who was a grandmother of the other three, so maybe my dogs were the result of some fortuitous decisions that Liz made. I know that she was very concerned about bringing in some new stock at the time that she stopped breeding.

Any thoughts?

Pat

Thanks for that -- glad you had a duplicate as it is so frustrating tolose a whole post!

I forgot that if you delete the first post of a thread the software assumes all the other posts should go too -- even though in this case the first two posts were duplicates.

I think there are some folks with thoughts out there who will come back to the thread in the morning as it is late over here == and I put out the question as well.

One response:

Goodness... This is a BIG subject.

Inbreeding is used to set type in the early days of a breed, and that
happens because the more genetically similar a dog is, the more physically
similar it is going to be, too - just what dog breeders want.

But there are two main costs to this kind of selection. The first is that
you risk the build-up of problem recessive genes (which are the cause of
most dog problems), and the second is that in chucking away the genes that
makes dogs different from each other, the more likely you are to compromise
the dog's ability to combat disease. The whole basis of sexual selection is
to preserve diversity because diversity is health-giving. It is thought to
be particularly critical for the immune system. And, typically, in very
inbred populations, you see an increase in immune-mediated problems such as
allergies and cancer. Inbreeding also often results in smaller litter sizes
and fertility problems.

As to where you'd draw the line... Well, Pat's dog is the progeny of an
aunt/nephew mating is pretty inbred. Assuming no inbreeding beforehand
(which of course there will be) this dog has a co-efficient of inbreeding of
12.5 per cent. The Swedish KC, on scientific advice, recommends a max COI of
6.25 per cent over 5 generations - the equivalent of first cousins.

But of course we're playing a statistical game here. Inbreeding increases
the risk of problems but does not of course guarantee them. You may get
lucky, at least in the short/medium term. There are examples of very inbred,
relatively healthy populations, but they are the exception - and in the case
of wild populations, natural selection has exerted a powerful influence.
Only the strongest and fittest get to breed.

Further reading:

http://terriermandotcom.blogspot.com/2006/05/inbred-thinking.html
http://documents.seppalasleddogs.com/html-documents/pbdb21c.htm

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