1)"HMC" - His Master's Choice
2)"Wardog"
3)"The Bully" - (Nothing to do with a certain Mr Isaacson. Down Under here a "bully" is a common slang name for a bull terrier - i.e. same breed as Spud Mac Kenzie the Bud dog.).
4)"K9" - well if it were a 9 incher...
5) The "10 Weiler"
6) "Hot Dog"
7)"JYD"/"Junk Yard Dog"
8) "Big bad boy" - The Triple B
9) "[censored] Biter"
10) "Steel Fang"

PS I have not read all the entries, so apologies if someone else has already used some of these.