Police pooches: US schools employ gun-sniffing dogs to curb violence – and bring students joy

Amid a rise in gun threats, firearm-detecting dogs become popular' safety measure that also has emotional benefits

As the new school year got under way in Tennessee, students in the Wilson county school district near Nashville welcomed two new school employees, Zander and Zena.

But they are not assistants or janitors, they are black labrador dogs on a serious mission - to protect the school community from gun violence and mass shootings in a country awash in firearms carried by the public.