nibbling

Question
I have a 20 month old miniature schnauzer.  For the last 5-6 months he has been nibbling, just with his front teeth, on comforters, towels, and even his own fleece blanket.  I have tried numerous times to get him to stop by telling him no, trying to remove him from the situation etc.  I am sure this is a behavioral issue, i just wanted to check to see what the best way to cure this is.  I do not know if this is possibly a problem that developed in the oral stage of development or what.  Please

Answer
This sounds like a highly self rewarding behavior and adding to the reward by giving the dog attention is most likely counter productive.  It may be a sign of anxiety.  Does your dog demonstrate any other signs of anxiety (like over barking, guarding the door, inappropriate elimination, licking his feet/nibbling his feet, etc.?)  Is your dog neutered??  "Nibbling", as you so aptly put it, is a pack related behavior (between dog and human or between dogs) but anxiety can certainly provoke this behavior, also BOREDOM.  Please describe any other behaviors your dog may have that further illuminate the possible cause of this particular behavior.  If there are none, I suggest you keep a daily record of when he demonstrates this behavior and attempt to define it by something environmental:  time of day, distance from feeding times, your presence or absence or leave taking, etc.  Introduce some positive reinforcement training and cue its beginning with a unique word (i.e., "pickle") so the dog not only becomes conditioned to performing the behavior (like "sit") but also to the cue.  After approximately 30 trials, your dog should respond to your initial cue by giving you immediate attention.  You can then use THAT cue ("pickle") to engage him in some brief play training.  This bridges the reward of play training with the nibbling behavior so the dog is not further rewarded for nibbling.  It won't extinguish the nibbling (since you can't possibly be there for every single event of nibbling) but it will give you a way to distract the dog and will also provide the dog with something positive he can to please you.  Often, simply establishing one simple command relaxes the dog's anxiety and eases the dog's need for self soothing behaviors.