There's a difference between a shelter/animal control and rescue.
Many of the dogs you see in rescue have been taken from a shelter somewhere. They're then usually placed in a foster home, where the people who are fostering them get their medical care, train them, evaluate them, socialize them, groom them and love them...just to make sure they get into the right forever home.
(The series of events may differ with each situation, but the end result is the same! )
Some stay a while in foster care...some only a short time. Others stay forever....because the foster family adopts them.
To be honest, I'm not sure what the "rules" are, and I've been here a while. There was a LONG discussion thread about posting rescues, whether or not it should be done on NN....and I don't really remember the final decision.
I believe that if you find one in need...in a newspaper, a flyer, a shelter, etc...that we've been asked to notify the closest (to that animal) Newf rescue in the area, so they can handle it.
If you don't know who that is...it's okay to ask in a thread, and then have the rescues PM you for more information, so they can research it better.