Having read all the replies to the original post, I can sort of see both sides of what happened, but I do tend to sympathise more with Bella that anyone else ....
Both my Cockers have been suddenly attacked and bitten, rolled and generally frightened out of their skins by other dogs - the owners are always soooooo defensive, and they ALWAYS say either 'Ooooh, he's never done that before!!!' or (as in Bella's case) 'Keep your dog away from mine!' when they are like 2 feet apart, and your little Cocker is already wagging its happy way towards its dooooom!
A pair of GSD-crosses used to regularly cross our path, and to be honest, if it wasn't for the owners yelling and fussing, they would probably have been okay, but they used to haul them around and make a big thing of grabbing their collars and walking them past us so that only their hind legs were touching ground ... no wonder the dogs thought that an encounter was something weird ... The first time we all met and they made such a big thing of 'keep your dogs away or else they'll have 'em ..' I said well why don't you muzzle them them, and at least they can socialise and play and once they realize they can't intimidate by biting they may be okay - their response was 'What, muzzle them? Then they would come off worst!' - I said that they were only assuming that everyone else's dogs were as chopsy as theirs, but they clearly would rather continue letting their dogs potentially chomp anything they meet rather than stop them having the ability to do so.....
There used to be one or two other culprits on our regular local walks, but thankfully all the dogs at present seem fine ... It is quite funny swapping stories with other dog owners though, and when you warn them about a certain dog/s, and say that the owner said 'He's never done that before..' and they say 'Oh we met them a couple of days ago, and it happened to me, and they said exactly the same thing !!' ... well ....!!!!!!