I have a friend in  Minnesota  close to Fargo, and about 1.5 hours from st. Cloud who needs some training advice and or trainer.

CC male pup 7 months old  was perfect family pup to 4.5 months went to puppy school and became dog aggressive instantly ( lives with 2 dogs non guardian breeds) Now I won't get into what trainer said all negative about mastiff's in general and she admitted to zero experience with them..her suggestion was to bring pup back with a 9lb lapdog from peoples home and as expected he did no better with him there in fact he showed aggression to that dog.

Whats happening now is dog is overly protective of home ( Owner is pregnant) he is staring down guests ( That he has met before)an has lunged but not bitten anyone No problem with family members ( husband wife a 8 yr old boy and a 2 yr old boy) They have to crate him till he calms down when guest arrive and than he calms a bit and they can let him out.

Now the cleaning woman can let him out in yard while owners away with no drama at all as well as 3 different people who come over when owners are away to let dogs out and feed them.

Need some hints on a local trainer or owner that could help out any ideas I can relay will be appreciated.