Hi gary there have been some good suggestions, i have personally had experience with german shepherds, rottie x bulls, and a mastiff/bull which i have at the moment, all of which have been great guards and have been more than adequate for the job. In my opinion the main thing is that you find people that are breeding from HEALTHY n good temperment stock which are bred to work as guards. Theres alot of options out there just the matter of which would suite you more, just look around well before you make your final decision.
I hope that helps some.
Fram
