Neopolitan Mastiff...

Those I have encounterd (just a few) tended to be more aggressive than the bulls or english.  That may have been the result of their handling.  However, practically all mastiffs I have encountered have been rescues in foster situation.  The neo was the only one that could never be rehabbed adequately for a new home.  She was not trustworthy with the other dogs or the cats; and hated men.  She has remained with the foster home (very skilled) and is under a regime of considerable management related to access.  I should state that my sample is very small.  I  also believe that Neo's are like Belgians.... In the right hands wonderful, but because of some less than stellar breeding practices "more fragile" of temperment and at risk for problem behavior when  placed in poor situations where folks do not understand them.

 I hope this is one is one of the lucky ones.

I've met 3 of them.  One was friendly, the other two were both dog and stranger aggressive.  Like a poster above said, there's rarely any middle ground with Neos. 

This is my contribution:

I have a neo mastiff and he is such a big baby. Even my 11pounds cat is capable of dominate him. And he'll came over me for protection!! When we walk, he would be curious and friendly with anybody (human, dog, cat) except at night... sometimes he'll bark to strange men, but never pull the leash trying to bite anybody. He's protective but no aggressive. And I really like that, because I live in Venezuela... not the safest place on Earth!

When he's playing with the cats, he's very concious of his size and very delicate with them. He knows when he can get crazy and play like a maniac, and when he has to be cautious and controlled, like with my frontdoor neighbour, she's 83, very fragile and afraid of any dog. Thor wouldn't even stared at her.

In the other hand, Thor's mother hasn't had any education and she can be very vicious with estrage people and dogs. But my personal theory is that her owners don't love her and she has grown pretty aggressive to protect her house. Nobody pays attention to poor Hanna and she doesn't have any toys or even a rawhide bone from time to time... only when I go to visit... and if I remember. Nobody walks her so is difficult to get her to the vet... I think if somebody will try to change her behavior, that would be a very hard work to do, but with love I think it will be possible.

And so on... I know nice neos and bad ones. Even one female which killed another neo when she was in heat, her stupid owner even let other two boyfriends came to try and they were killed too...

I'll recommend to take that neo, only if you test him carefully. I'm sure, if he is a nice dog with no traumas or bad responses, he'll be a very good friend to you and your dogs.

my husband trained one once, back in the 80's. this dog was bought by his boss to be a junk yard guard dog.. he got him from a female flight attendant that could, for obvious reasons, no longer keep him..... the dog was TOO good at his job. people would sneak into the junkyard at night and the next morning the boss would find bloody clothing, shoes, etc.

but paying customers could not go into the junkyard for parts as long as the dog was loose, thus he had to be chained 24/7.. long story short .. my husband was the only person to 'reach' the dog. this was after some brute with a baseball bat and raw hamburger failed to "train" him.. my husband doest spend hours reading books and following training methods, but he did right with this one.

 however i have met some in the AKC shows. nice, friendly, well rounded, level headed etc. but thats a credit to who ever trained them!

my own opinion is these are still old world mastiffs and retain a good deal of their guarding instincts like American Bulldogs, Canary Dogs, and the like. Very dominant.... this is not a breed to be taken lightly, especially if it has been mistreated... Chaco, the one my husband worked with, was a murderer until he found someone he could trust and not bully him around. but by the time he was finished with him he discovered the dog was indeed VERY well trained, would sit, stay, heel, you name it. if you said stay the dog would not budge for hours until you called him.