I have worked with dogs for over 30 years, as a groomer, a trainer and a behaviourist.
Dogs and small children should NEVER be left together unsupervised. Until a couple of years ago, I had 6 border collies. My eldest DGD who was 3 at the time, begged me to let her come and help at feeding time, the dogs at that time were fed in the garage which was at the end of the garden. I walked up the garden holding onto her hand while the dogs walked around, sniffing and wondering who this little human was. After we got back to the house, I was horrified at what I had done and it never happened again, no matter how much the little girl begged to help. All it would have taken was for her to trip and fall or even give a high pitched giggle and the dogs, collies being inclined to be a bit nippy, could have turned on her. The thought of what could have happened still haunts me to this day as the pack instinct could have kicked in, there was food added to the equation etc.
4 of the dogs were elderly and sadly are no longer with me but now, having 4 GC, when they come to stay, the remaining 2 dogs stay quite happily in the garden and are only let in to socialise with the children under my very close supervision.
Many years ago, I read of a very sad case where a family with a small child found the child distressed having been bitten badly by the family dog. The dog was taken to the vet and put down. Lying dead on the vets table, an animal nurse noticed something strange about the dog's ear. Upon closer inspection, she found that a crayon 6 inches long had been rammed into the dog's ear canal.
NEVER leave a small child unsupervised with an animal until they are old enough to understand how to behave around them.
Dogs are not small, furry humans, they do not think like us and yes, as someone previously mentioned, they discipline their offspring by nipping them! Some dogs will find the high pitched voices and running around of children distressing if they are not used to them and unfortunately will respond with a bite.
DO NOT take that risk.
Alexa I couldn't agree more, having worked with dogs for so long, what constantly amazes me, is that there are not more cases of people being bitten.