As KamalRaj mentioned all above breed needs a strong and firm owner which can handles the muscular breed. But ya if the dog would be trained for obedience and security it could be handled by a senior. Also this is not a one time expense, it includes all the vaccinations, vet visits and commercial dog food- (if not fed home food). My lab costs me average 1k-1.5K per month, even i dont feed him commercial dog food. But Home made food--Roti, Rice, Dahi, chicken or meat, paneer, eggs, bread. And also keep in mind 3 times walk daily for his business and playing.