Dogs can detect boxes that contain electricity from those that don't.

It is widely known that dogs have an excellent sense of smell, but
scientists are still discovering how advanced dogs' smelling capabilities
are. Dogs are able to smell many things that humans cannot. For example,
dogs can detect boxes that contain electricity from those that don't.
Researchers believe dogs are able to smell the tiny amounts of ozone
released from electricity, thanks to their keen sense of smell.