This is a brilliant post from 4paws uni about on lead dog aggression, what makes it worse and what you can do to make it better or at least relieve your dog's stress.
Every day I see someone whacking their dog for being bad on lead. Which is appalling to me - because hurting your dog like that, will only make your dog blame the other dog for its pain and humiliation. Which will lead to even more aggressive displays intended to drive the other dog away before it can get your dog.
On-Leash Aggression, Leash Reactivity, Dog Aggression
I found I might be doing something wrong... my dog currently hates any unknown curly coat dog. Some days and places are worse than others. So if I see a curly coat dog before she does - she goes on lead until the curly coat dog is "out of range" but sometimes we get into trouble because the curly coat dogs almost always want to get in her face and their owners are entirely clueless. So even if we're walking away as fast as we can - we sometimes still encounter the rude curly coat dog.
Mostly what I have been doing - is holding her by the collar and preventing her from moving - which the article expressly says not to do. But it sometimes works because it stops the other dog from approaching because she's not moving or interesting that way. But not always - some will still jump on her head despite the ferocious noise she's making.
And I can't tell them because if I yell at someone - even if it's just a distance thing so they can hear - my dog feels she must help me yell and joins in. And I can't go talk to them either because my dog goes nuts. But she also knows I'm pissed at this person for letting their oodle jump all over my dog's head without a proper introduction. sigh.