The Summer of 2013 officially began only last Friday, but already it has a good shot at achieving a dubious distinction in the annals of parental indulgence. This could be the summer that ice cream trucks for dogs go mainstream. Ever since the K99 ice cream truck set up shop in the parks of London during the summer of 2010–to the tune of the Scooby Doo theme song, no less–the trend of cruising trucks full of specially-made canine ice cream treats and cookies has been spreading and appears to be hitting its jaunty stride. Last summer, they started dropping by...