The nice thing about the current incarnation of Dick Tracy is that it can be enjoyed on several levels. Thanks to the masterful work of Mike Curtis and Joe Staton, whether you have extensive, average, or virtually no knowledge of the strip's rich history, the daily sequence will usually work for you and forward the story.
Take this example from April 20, 2015. (click to enlarge)
If you no little about the strip, you can take it at face value. A police dog has been called in to search for clues. He's good at his job. Tune in tomorrow.
If you know something of the strip's history, you may experience a shock of recognition. The name and appearance of the dog are identical to one who first appeared in 1949. Chester Gould (Dick Tracy's original creator) introduced Mugg in the story arc about the con man Pear-Shape. Mugg was adopted by Dick Tracy became a police dog. He appeared off and on in the early 1950's. So you could see this as an homage to the postwar Dick Tracy.
If you know a lot about the strip, however, then you know that in the 1990's Dick Tracy's son, Joe, was given one of Mugg's pups, who he named Muggsy. It was intimated that Muggs had died (presumably of old age). Another descendant, Muggs III was introduced in 2011 as a member of the K-9 corps. Mugg III, of course, is the one depicted in the sequence above. And if you do know the whole story, then you get the full meaning of officer Doherty's comment, "Muggs comes from a long line of K-9's."
He does indeed.
One sequence, three levels of meaning.