I have two dogs a brother and a sister dog. They Are Minature Pintures And They keep trying to mate and I am worried that the puppies will be retarded or she will have complications.
This is not apt to cause complications but potentially could cause problems in the pup's health.
In general most dog breeders would not choose to do such a close inbreeding.
You need to know a lot about the health of all the dogs in the pedigree back at least three or more generations to even think about feeling safe in doing this.
You could double up on unsuspected recessive traits and have problems.
You may also get a smaller than normal litter if some of the fetuses don't make it to being born due to defects.
You might want to read more about inbreeding and other breeding methods to understand the risks.
You can read about the pluses and minuses of inbreeding here
A lot depends on how much you know about the bloodline of the dogs and their ancestors health how safe this might be.
And if you plan to sell the pups you may find puppy buyers are not happy with you if the pups have hereditary problems.
Hope this helps you!