I would say something or ask the council to put up signs.
DS1 screams if a dog comes too close to him. There is no way he would play somewhere with dogs off leash.
On another note I also hate when adults gives kids control of a dog on a leash. DS2 had a dog get in his face because a 6 yr old was holding the leash and I had to quickly pick him up off the picnic blanket. (We were watching soccer) meanwhile the mum and owner were sitting further away paying no attention.
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