Not all dogs who see hulking, noisy garbage trucks react to them, but many do. For those dogs, encountering one while they’re outside can provoke them to chase it, or to erupt in a frantic bout of barking and fence-running. Seeing it while they’re inside the house may set off an attack of frenzied barking at the window.
What is it about garbage trucks that upsets dogs? Pretty much everything. They’re big, they’re loud in a whole bunch of different ways, and they stop and start frequently. Heaven only knows how dogs feel about the variety of smells that emanate from them, but there’s certainly a powerful olfactory component. On top of everything—in towns and cities, at least—they pull up right in front of the dog’s house.