Our rule is to ask the owner before stroking a dog - which I know means we are relying on their judgement of their own dog. Being a judgy pants though I would only allow DD to ask if I liked the look of the dog/person combo! I think you dealt with it really well and what you said will have helped DD and hopefully the owner to understand the dog's reaction.
Sounds like you handled it well - not sure how you could have done it much better.
The only thing I'd say about kids stroking dogs which you didn't mention is that it may be best to stroke the back rather than anywhere near the head - less likely to spook a dog, and further away from the teeth if it decided to snap.
You did the right thing. It sounds like the owner doesn't quite understand his dog's reactions which could become a problem. If the dog's warning signs are not taken into account, he could become more anxious and more aggressive. You did right to warn him, I hope he takes it to heart.
Was walking on path back from preschool busy residential area. Dd and her friend were slightly ahead and I caught up. As they were saying goodbye a Jack Russell rounded the corner on an extension lead. I've met it before, her owner has some SN and limited mobility. I think this is why the extension lead.
Dog runs up to dd (holding my hand now) and very interested in dd, body language fine. Dd smiled but didn't move). Owner says she loves people and invites dd to stroke her. Dd bends down with me and as taught holds her hand out for the dog to approach her. She went to stroke the dog and at the last minute the dog very clearly got anxious and snapped. Air snap, nothing more. Dd backed off.
Owner was clearly upset, and said she's never snapped before she loves fuss. Meanwhile the dog was desperately trying to approach dd again, floppy body tail fine. This time we both held out our hand, dd stroked her chest. Dog was fine this time, till dd stopped stroking and stood up, then dog showed eye white and licked lips.
I pointed this out and asked the owner if she was used to children. He said yes, his niece carries her around lots and the dog has been told off when it gets rough or has barked so should be fine with children.
I told him his dog was lovely but obviously wary of small children, this really upset him, I said it may be best not to invite children to pet her anymore and keep her on a closer lead when little ones are running around, so she isn't scared. As not all children are used to dogs like dd and might really scare her. I also said his niece needs to give her space and treats not pick her up and the dog shouldn't be punished for getting rough if she is manhandled by a child.
He was clearly, really really upset by the snap. And I have never wished harder that I was one of you lot, who would have handled it much better.
(And yes, I have realised that the easiest thing would've been to have never have let dd accept his invitation to pet the dog)