Not a common sight

We walked past this bench this morning and I had one of those double take moments.
.... and then the questions flooded my mind...

Who leaves a dog's muzzle on a park bench?

If they are typically used on dangerous breeds, where exactly was the ex-wearer of the muzzle?

If it was worn by a greyhound, where had it raced off to?

Was a dog set free by supporters of canine manumission?

As I said, not a common sight, and one to naturally spark many questions and theories.