How could one talk some sense to a person who asks on another site:
"I want to breed my German Shepard and she is 10 months old is this too soon? I'm not sure if she has had her period will this affect her to breed? " 

Breeding a German Shepard at that age would be really wrong , a bitch should not be mated until maybe her 3rd or 4th season , which would make her 2 years old.

There could be serious health hazards for a bitch that was mated that young , maybe this is what you should point out , she may also not be able to cope with a litter at that age , as she is not yet fully matured , and handraising puppies is extremely hard work , that could be something that could well happen.

She is not even old enough to be hip scored , and German Shepards need to be tested for hip displasia prior to breeding.

If you think of a 2 year old dog as the equivalent of a 20 year old woman, both just starting on there best reproductive time, then to breed a 10 month pup is like suggesting that you breed an 8 year old girl with all the same problems.

As sad as this situation is it happens all the time and it will not matter what you say, how can you talk some sense into a person that clearly has none.  If I were you I would not waste my energy, you will end up wound up for nothing.
Also people post these messages with the intention of winding you up, you get them here too.  Kind regards, Debbie.

Stop the world I want to get off.