The first thing a pet parent should remember is that each dog is an individual, and as such his sensitive area(s) will vary from dog to dog. With that being said, I’ll be using my girl, Alex, and some of her furry friends, Gir and Roxy, to illustrate my point.
Alex’s sensitive area is her rump. Years ago, when she was a little under a year old, I tried to move her by touching her rump and she growled at me. I was pretty surprised because Alex, even as a puppy, was always very easy-going. What did I do? I worked with her, little by little, using treats so I could get her used to having someone touch her “sensitive spot,” and after a short while she was fine. But, even after all these years, I still have to be gentle when I am brushing and wiping her cute rump. She never growled again, but I am always aware that I need to be more careful when it comes to her sensitive area.
Gir’s sensitive spot is his ears. Once, while petting him he moved away from me while trying to nip me when I touched his ears. What did I do? Every time I touched his ears just for a couple of seconds was after our long walk, and while he was asleep on my lap. He seemed to mind less and less having his ears touched.
Roxy’ sensitive spot is her hair. Yes, her hair, and she has lots and lots of hair. Roxy’s mom told me that she did not like to be brushed very much, so from her very first stay with us I took her for long walks, followed by a nice gentle session of brushing and wiping. I did not use treats, but rather exercise to desensitize her to the brush, and get her to associate brushing with something pleasant. Since Roxy comes to stay with us often, she knows our routine:walk, brushing, wiping, and breakfast/dinner, and does not mind being brushed any longer.
Once you figure out your dog’s sensitive part, make sure you work alongside a reputable behaviorist or dog trainer on desensitizing him to whatever it is that is causing him to growl, nip, bite, etc. The examples I used to illustrate my point are that of dogs that are not aggressive, exhibiting symptoms that I’d consider mild, but I’d strongly recommend to consult a behaviorist or dog trainer to help you with these type of issues, and remember that what works for one dog may not necessarily work for another.