> my dogs have 11 moths between them my males DOB is 13/6/05 and my bitch DOB is 23/5/06 now they have exactly the same parents and both KC reg hth
This may mean the mother had a season in between, or may be a bitch with long inter season intervals mated on the very next season. Only the bitch owner will really know.
The first most people would find perfectly acceptable (in your case it's 20 days less than 12 months), but the latter scenario (except in rare cases like a singleton puppy, death of the litter etc), less so, though so nearly 12 months again most people would say 3 weeks wouldn't make a bitch less fit to rear a litter than 3 weeks more.
In the case OP refers to the bitch has had a season between the litter and the current one that the OP's friend wishes to mate her on, but that will result in 10 months between litters so the bitch must be having 4 or 5 month seasons.
This is one reason the KC did away with the 12 month ruling, not to encourage people to mate a bitch too soon after a litter, as in the very next season (though in rare cases this is acceptable), but to allow for the fact bitches are not automatons and do have varying inter season intervals.