Of Dogs and Days

Every dog has its day
this is true, or so they say.
Assuming this you see,
that a single day is all it be.
When day meets its night,
and the dog has finished its fight,
the dog will fade away,
every day melting into grey.
Nowhere to run.
No chance for fun.
Tension drags life into the void,
for all its purpose has been destroyed.
It yearns for its final breath
because after its day, every dog has its death.