masculine names...
Hmmm... You know when I one day am blessed to own a boxer I am looking into olde english names... or using names from Rohan (yes I am a huge fantasy sci-fi geek). I would recommend Framgar, it means valiant spear. Or Guthulf another olde english name and plenty masculine. Of course comming up with call names can be fun but my favorite name, one I hope to use for a dog of mine one day is Theoden, and that one is easy to shorten to Theo or Denny. And it might just be my opinion but how can one have a more masculine name than that of the king of Rohan!