Annoyed

Dogs can be dangerous when not trained/controlled by the owner. They are animals before they are pets. So no your DD is not overreacting, she was behaving like a sensible parent. The grandparents are at fault here as your SiL should point out. Is for him to deal with this rather than put your DD through dealing with his parents.

Totally unacceptable.
Dogs should not be a threat to adults and children.
I spent part of my childhood with farm dogs and my adulthood with three or four mainly rescue dogs -if they posed a threat to anyone I rehomed them if possible.
I know of a lady who lost part of her mouth to a snapping dig which was a pet .

Where is your son in law in this? He should be defending his wife and telling his parents that their attitude is unacceptable.

Well, if your daughter was aware that the dog was not people friendly why would she agree that her in laws bring it on holiday with the children?

Much as I love dogs, I can't bear the ones that the owners won't control.

Over the years I have been bitten, knocked over, covered in mud, had food taken, an expensive glove ripped to shreds and scratched by dogs. I am aware that it is not the dogs' fault and it is up to the owner to train them.

If my children had done half of the things that some dog owners seem to think are acceptable they would have been in serious trouble.

Most dog owners are very responsible and their dogs behave properly but there seem to be a few who can't or won't see that their dogs are a nuisance. Your DD is most certainly not overreacting it is the other grandparents who are under-reacting to what was an inexcusable situation..

had she not met the dog before going on holiday

Your SiL should have told his parents that the dog’s behaviour was unacceptable and that his wife was being injured by it. The GPs prioritised the dog, your SiL did not prioritise his family. I’m hoping that the bite was accidental, if it wasn’t then the children are not safe around the dog and your DD should tell pil that she and the children won’t be visiting them again if the dog is around.

If \ IO was that mother, the dog attack on my child would be reported to police.

Then let the dog owner tell the police their response is over reacting.

She made it clear that she obviously wasnt happy ( who would be) It isnt a young dog

Has the dog always been like this, or is it the amount of people/children that have been on the holiday?

I just cannot understand their thinking. The warning signs were there and they obviously ignored them.As a grandparent why would anyone do this.
I just dont get it.Im so annoyed that my grandchildren were put at risk

I don't think it's acceptable. I have friend who's dog constantly jumps up at anyone who comes to the house. I'm on blood thinners and the dog's nails are sharp. I've explained this but she's allowed the dog to do this since she's had him so he basically ignores her. I can bleed easily so only invite her here without the dog. Unacceptable with young children, no dog can be completely trusted but some owners know if there dog is friendly or not with children. Has she had a tetanus jab?

Surely your daughter knew what the dog was like before deciding to go on holiday with them. Did she say anything whilst away. What did they say
The one thing not mentioned was it by chance a young dog

Of course totally unacceptable and bad behaviour. What were the other grandparents thinking? Parents don’t want their children or themselves damaged in any way by dogs. What is wrong with the dog?