The late Mr. Wolters' information is actually quite up to date for the average home trainer. Most of what he has written is for the average hunter and is geared toward what someone would need to do if they wanted to raise and train their own hunting dog. While the results are not exactly what a professional trainer would accomplish (the methods are somewhat watered down and Mr. Wolters even said in his books this isn't meant to replace professional training for a test and trial dog) the results are good enough for most hunters' needs.
Many "modern" trainers who are being fed the "positive only" kool-aid say that his methods are outdated and barbaric however the methods he outlines are simply softened versions of the methods that successful professional hunt trainers have used and still use today to create champion hunters.
I do warn you though that if you delve into the training methods that professional trainers use you'll have to be able to clear your mind of the "positive only" and "soft" training that is being force fed to the general public. These methods are not used by successful trainers (they don't provide good results consistently and on a good time line).
Now with all that said I would like to echo what PawPaw said regarding hunting dogs. There are many types of hunting dogs and you will find that professional trainers will specialize in the type of hunting dog they train. I personally work with flushing retrievers - I train duck dogs and upland flushing retrievers (pheasants and other upland game birds). Other trainers train for ONLY duck dogs or ONLY flushing upland retrievers. Others yet will only train for pointers (some pointers retrieve, some don't and there are trainers who train one way or the other). Then there are various specialties in the earth dog field of hunting dogs. These are the coon dogs, rabbit dogs and other dogs that are trained to hunt small game. They are trained (by specialization) to find, flush, bay and tree, kill, retrieve, go to ground (follow the game into a burrow) and any combination of the above. Generally trainers do not cross specializations.
So when you ask about hunting dogs you have to be clear about what sort of hunting dog you are referring to.
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