The speaker has spots in their vision, the kind that float and refuse to fade, and responds with a bit of wry, dog-like play. Riding in a car, they stick their head out the window like a dog, eyes watering in the wind, half-hoping the speed will smear the spots into stripes. The opening joke, "Do I smell of dalmatian?", sets the tone: the speaker is worried, but chooses humor over panic.
The spots don't give way. They stay "sharply delineated," blank patches that sit in the view wherever the speaker looks. The closing image compares them to a stray cat slipping in to drink milk, and the word "lapidary," suggesting something cut and precise like carved stone, makes them oddly beautiful as well as irritating. But they can't be caught or fixed in place. The final line, "Impossible to catch," leaves a quiet unease under the playfulness. The mood is light, a little rueful, and slightly anxious: someone laughing at a problem they can't shake.