Powerful dogs need a firm but also loving master from day one.
I've a 7 year old, 8 stone German / Belgian shepherd cross who I have had since he was 7 weeks old.
To put it bluntly, he scares the shite out of most people due to his size and his manor.
Basically, he is a bloody big puppy who thinks everybody is put on this planet to be his friend and play with him BUT being a shepherd, his first instinct is to protect and if he see's you as a threat due to YOUR demeanour then you will get a warning

He is my best mate and a member of my family and he gets treat as such but if he steps out of line then I have in the past slapped him around when he has done wrong and will do again if need be

There is NO such thing as a bad or aggressive breed of dog, just piggin thick owners who just haven't got a clue how to bring one up
If ANY dog has been brought up badly then it will be aggressive and uncontrollable and there is sweet F A anybody can do about it and if it can't be trusted then it should be put to sleep along with its owner

A few on here are talking about breeds............. well here is my take on it

A powerful dog is just a affectionate, loving, mild mannered and safe around children as a yapping handbag accessory that some folks seem to think are the ideal pet IF BROUGHT UP PROPERLY

The Only difference is ............... the strength of the bite

PhilRich, sorry to hear about your lad.
Hope he gets well soon