Each breed of dogs has their own maturity age and it is not advisable to breed a puppy age of 6months.
In my own opinion the earliest possible breeding time for them is their 2nd heat or 1 year old +
- too early
- 75-80% premature litters
- not ready to be a mother
As for qualifications of papers like PCCI they are accepting 8months of age of mating which sometimes unavoidable.
The PCCI will only accept for registration a litter that is out of a
- dam that is between eight (8) months and ten(10) years of age at the time of mating
No dog or litter out of a dam under eight (8) months or over ten (10) years of age at the time of mating will be registered. Litters our of a dam over ten (10) years old at the time of mating will no longer be accepted for registration.
link of Pcci