If there were serious health issues, I could understand your fury, but as far as I understand the problem, the only thing that could have happened here is that your dog might become temporarily unshowable due to hair loss. Undesirable though that may be, it's not much of an excuse to curse about small children behaving like small children.
If in future you want people to understand your first priority is your dog's health, you might want to mention it specifically. Not everyone on this forum knows you, and what you write in any post is what most people will judge you on. I initially assumed you were worried about your dog's health, but after the third post mentioning how detrimental it was to his show career to lose his coat, it seemed a little less obvious.
Maybe she was getting ready for a specialty. Did you ever think about that? A show dog's apreance MUST be impecable. Do you realize how important that is to some people?
Who are you to judge because she is upset about her dog loosing his coat?
I would be furious if Emma lost her coat due to someone else's stupidity and not watching their kids. Emma's not a show dog. How do you know it whont be VERY uncomforetable for the dog to loose it's coat? Itchy mabybe?
Dont judge people because they show their dogs.