Are dogs suppose to expel their glands naturally?

I'm a new dog owner, so this subject is new to me. I've read it should happen naturally, but also read you have to take the dog to the vet or learn how to do it at home. I have a 17 lb Jack Russel/Corgi mix and didn't know if the breed of dog matters in this. Pardon my ignorance. I am trying to learn. :)