Looking for advice I have been asked to stud my boy with a relative they arent close the bitches sire is my dogs half brother from a previous litter before  have the same father but not the dam . So would be  half uncle to great half niece I'm so confused on it have said no but would like to back up my answer .

There isn't an issue with line-breeding, so long as the breeder knows what they're doing - I know quite a few stunning examples of the breed which have been line-bred, doubling up on a quality dog. It's the generations after them where more caution is needed regarding who they'll be put to.

And for those who try to say it's "inbreeding" and "humans don't do it", try telling the royal family

I suggest checking out the coi and health tests on the KC website and take it from there.

Dobermans are incredibly inbred as a breed anyway - and in a mess, health-wise as a result :( 

I know old time breeders will pronounce the benefits of line breeding to fix traits but seriously we are facing the catastrophic end of healthy pedigree dogs - unless we can all take genetic diversity seriously and do our individual bits to prioritise it.  Each individual breeder only 'just' breeding above the average COI results in massively increasing COIs over time...

I would have said no just because of the change you will find in your dogs character.

I can say that after a number of outcross matings (mainly because living in Canada with my English imports, I had to go out - breeding for type rather than bloodlines) eventually and back in the UK and with a couple of further outcross matings as I wasn't able to pick up my English lines back home, unfortunately,  I decided to do two close matings to see where I was.  I bred uncle to niece and aunt to nephew.   The former produced a decent litter although they were all males (!) and the other just produced one puppy, a bitch.  BUT the mother only had 2 puppies, to an outcross mating before that so I didn't put only having one puppy from her second (and final) litter down to it being 'close'. 

You do have to be able to recognise the faults your stock has, and ditto for the female whose owner is interested in your dog, and what's back of their bloodlines (recessive genes) regardless of how close really. 

In any case, would think long and hard about allowing your boy to be used 'at public stud' because believe me, any problems that might crop up will inevitably be blamed on your dog.   It's the way of the world.    And for sure, the owner of the stud dog is 50% responsible for what he throws.

Virtue's can be intensified but so too can faults, its a roll of the dice.

E.T.A. Knowledgeable breeder's have done wonders line breeding (half brother mated to half sister etc etc) but having the knowledge of the dogs in the pedigree is key.

Also assuming no other common ancestors the COI for half uncle to niece/half aunt to nephew mating is 7.5% and less related than first cousins, which in humans are allowed to marry.

The virtues and faults of both parents and their ancestors need to be taken into account.

It also helps if there are healthy adult offspring of the proposed parents to assess.