On of many problems with so-called "invisible fences" is that they are indeed invisible. Being new to neighborhood, the shooter probably had no idea the dog might be restrained by the device. From his perspective, the only thing standing between he and his kid and a charging mouth full of teeth was his marksmanship. Because I love most dogs more than I love most people I hate to admit it, but were I in a similar situation I might have responded to the perceived threat in exactly the same manner.

Both parties have my sympathy.