Mating a half brother to a half sister.

[madrags]

Marriage to first cousins is unlawful in many states in the USA http://marriage.about.com/cs/marriagelicenses/a/cousin.
The risk of genetic defects occuring in children of a cousin to cousin partnership is twice that of children of a relationship between unrelated couples, providing that there is no known genetic defect. However, the likelihood is bound to increase if marriage between cousins happens several times within the same family. Double first cousins have the same consanguinity as half-siblings. I have come across some such problems in the course of my work, and a friend of mine has a familial neurological problem, similar to Friedrich's ataxia.

[arwesa]

- Linebreeding/Inbreeding does NOT create dogs with bad health. It simply shows what is hidden in the genes. By outcrossing it stays hidden, but it isn't gone. By inbreeding it allows you to see what is no longer hidden and do something about it. This means culling. Yes, if you want to progress you have to look at dogs as tools and cull what isn't O.K.

Unfortunately we all know culling doesnt happen in todays world. a breeder gets 8 pups, keeps one and sells 7. he has no idea if any of them have inherited future problems and probably will never know what happens to most of them.

I think your opening scentence is mildly naieve... if you inbreed you know you are increasing the chances of genetic abnormalities in the dogs, yes that doesnt necessarily mean that pup is visibly unhealthy, but it does put future breeding (which is out of the control of the modern day breeder as there's no culling ) at risk. FACT - Inbreeding causes genetic abnormalities you cant see FACT- genetic abnormalities can result in new instances of disease FACT - higher COI the hicher the chance of genetic abnormalities being created FACT - genetic depression (prolonged inbreeding) causes other problems such as reduced litter sizes and breeding issues

(Im using abnormalities instead of the genetic terms you'll find if you read the links posted earlier..they mean the same thing)

Im going to try and keep my future breeding to between 6 and 12% I believe this will allow me to line breed to maintain type with outcrosses for diversity and to introduce desired new traits.

Im sure thats not very different to many on here, but why play russian roullette with the breed future by not controlling the amount of overlap?

[vicky payne]

I just can't understand why people can categoricaly say in-breeding can produce the best dogs BUT that it doesn't increase the risk of bad dogs. Close breeding increases the chance BOTH of getting the traits you want AND traits you don't. Perhaps diseases we don't even know about yet. The old in-breeders knew their lines inside-out and had no inhibitions about breeding very young dogs together and killing anything that wasn't right.

I ask again; do we want this in the 21st century?

It is asked if we don't test a dog enough by sending him for a duck in a fast flowing river. Yes, we test his phenotype BUT we don't test his genotype. A dog can have one bad copy of a gene and will show no signs of the disease himself, ever. Mate him with a perfectly normal looking bitch who happens to carry the same gene and 1/4 of their pups will be affected by the disease. Inbreeding increases the risk of doubling up the bad genes BUT outbreeding doesn't necessarily avoid it if you don't know more about what you are putting together than their COI's. I have seen two F2 labradoodle with elbow dysplasia. I'm sure their COI would have been low, but a failure to health test caused expensive disasters.

The understanding of genetics is not some threat to traditional dog breeding, just another tool. Really.

[scot-ish]

aiming for a specific COI imho is not how breeding should be done. if you like a sire, and think it will compliment your bitch, use it, wether litter coi is 12% or 20%

[vicky payne]

OK scot-ish. But what if there were two studs you liked equally....and on paper both had lines which you thought would compliment your bitch. Imagine both are equally succesful in trials (if that's your aim) and have both had the requisite health tests. They are equidistant from your home and he stud fees/erms are the same. Now....on mate-select one mating comes in at 20% and one at 12%. Tell me you're still going to just toss a coin? That's how I'd use it.

[arwesa]

OK scot-ish. But what if there were two studs you liked equally....and on paper both had lines which you thought would compliment your bitch. Imagine both are equally succesful in trials (if that's your aim) and have both had the requisite health tests. They are equidistant from your home and he stud fees/erms are the same. Now....on mate-select one mating comes in at 20% and one at 12%. Tell me you're still going to just toss a coin? That's how I'd use it.

agree 100%...exactly as Ive repeatedly explained Id like to use it..

[scot-ish]

OK scot-ish. But what if there were two studs you liked equally....and on paper both had lines which you thought would compliment your bitch. Imagine both are equally succesful in trials (if that's your aim) and have both had the requisite health tests. They are equidistant from your home and he stud fees/erms are the same. Now....on mate-select one mating comes in at 20% and one at 12%. Tell me you're still going to just toss a coin? That's how I'd use it.

the chances on a situation like that are highly unlikely, you will very rarely find two stud dogs, which each have the same attributes, nearly everydog is different, and i wouldnt be looking so much into the lines, mearly the sire/dam of the stud dogs and how they worked, and any other offspring produced by the stud dog.

but one giving 20% COI and one giving 12% COI wouldnt influence my decision, as i wouldnt let the decision come down to that, so on that point, and the likelyhood of finding two identical stud dogs, i think the mateselect has a use as an observation tool, but otherwise regarding breeding, i dont think it will influence myself, and dare i say it, the top men around trialling.

[vicky payne]

ok

[arwesa]

, i dont think it will influence myself, and dare i say it, the top men around trialling.

Cant you stand by your own convictions without trying to resort to association by representing views of others without KNOWING their views? generalised statements claiming the 'top men' around trialling dont care about COI's and inbreeding?

Perhaps the 'top' men and women around trialling care about breeding, care about their lines and choose carefully. some I know look at COI (tends to be lab people as their ahead of most other breeds in that respect)

Drakeshead...range of FTCH studs, COIs 4.1 to 8.5. +/- 2% of breed ave (labs)
Buccleuch ....range of breeding bitches 8.1 to 11.9 max +3% over breed ave (ess)
Edgegrove....range of studs 5.4 to 11 +/- 3% of breed ave (ess)

not exactly extreme inbreeding there.

It seems to me some people in the cocker world have a challenge with inbreeding and would rather bury their heads in the sand than confront a difficult issue and plan for the future...

[CROFTPLACESPANIELS]

I think we are all going to have to agree to disagree. I can see the point of of line breeding but I feel the breeders doing it need to know there stuff and know about the history of the offspring that line has bred. I haven't looked to much into the mate select idea yet. But I would have thought if the kennel club has put a maximum COI they must have been advised by a group of experts.
The same applies to Health testing and not to Health test at the end of the day its the breeders decision to produce a litter to fit there criteria. The kennel club have came up with the Accredited breeder scheme and mate select to give breeders more information to make an informed decision.