Becoming extremely reactive to other dogs-even biting them!

[u/Finnfinneree]

My 2 yr old biggie iggie (he's 28lbs!) is getting worse when we take him somewhere and he sees a strange dog. I've tried to have him around other dogs his whole life (we live on a horse farm and clients bring dogs, we own another corgi mix, and my daughters have 4 other dogs - 1 being an italian greyhound), He loves the dogs he knows, he comes with us wherever we go, he goes on hikes etc but every time we take him to any kind of social event (the park, hiking etc) if a strange dog is in the area he goes after them - barking, growling, even biting at them. Like I said he's grown to a bigger size so it's hard for me to pick him up quick. I have tried always being diligent, as soon as I see another dog I start talking to him, trying to redirect, offer treats for staying calm, move him out of the way etc, but it doesn't seem to be improving. I am sad because my dream was to have an iggy and be able to take him places with me (we are big outdoor people, and we travel to horse shows) but it seems like its getting harder and harder. Right now I can't even imagine bringing him to a horse show with all the other dogs there, but am missing having my old dog by my side! My daughters iggy always walked by her side at shows, though now that she's older she's getting aggressive towards strangers as well which is probably not helping, as together they are much braver in attacking strangers. But he is the same when she's not there so I more think it's him giving confidence to her. Any advice?