Sorry I totally disagree with the posters above.
Loads of scientific studies that show the only behaviour that will be prevented after castration is scent marking. Humping, energy levels, etc will not change a bit.
What often happens is that is coincides with the dog maturing anyway.
Working cockers are manic ( I have working dogs, collies, kelpies etc all my life and will never ever ever own a working cocker, fostered many though!!!)
You need brain activities, you need exercise, you need training, constantly, to have a calm working cocker.
Have him castrated for health reasons and prevention of breeding but I promise you that castration will not make any difference to his energy levels.
Dominating behaviour is rubbish by the way as I am sure you know
Comparing a german shepherd to a working cocker is not the same at all
. German shepherds are intelligent, empathetic, sensitive dogs, working cockers are just on speed instinctively driven by scents and the need to chase 