Children can be seriously injured by dogs partly due to the reaction they have when things go bad. Most kids flail their arms and scream, like injured prey. So this entices the dogs to push their attack (there is a reason dog toys have sqeekers).
As for toy dogs being violent, I have seen unruly miniature pinscher

, draw blood (though it was a very small amount for an adult). I still think that you need to monitor small children around dogs, and if you have a dog off a leash
you must control the enviroment.