You have been chasing a critter through multiple back-yards. He is half your age and not encumbered by the forty pounds of bat-belt and armour required by Modern Policing; therefore he is actually picking up speed as he antelopes over fence after fence after fence.
As you are leaning against a tree, wheezing and swearing that you're going to start going to the gym tomorrow, he clears the next-to-last fence -- to the sudden joyous baritone barking that can only come from the throat of a dog the size of a tyrannosaurus rex.
This is techically referred to as "Canis Interruptus", and it tends to engender a warm-and-fuzzy feeling in your chest and a jaunty whistle to your lips as you stroll happily down the alley to the heartrending sounds of shrieking, tearing, crashing and general doggy mayhem.
This has been your LawDog Phrase of the Day.