Panel 1: We start off with Elly thought-bubbling "Darned dog" because Farley's barking because he's been left outside to go crazy by his idiot owners again disrupts her going ticka-tacka-tappa about being the library mule.
Panel 2: She then does the very futile thing she does of talking to Farley as if he can answer her back and asks him what's the matter with him.
Panel 3: She then tries to convince him to stop barking by telling him that given that the squirrels are hibernating and the birds down south, there's nothing for him to bark at.
Panel 4: Liz speculates that this is why he's barking.
Summary: The problem is not just that Elly is too stupid to remember that Farley isn't a big, shaggy lump she can forget for days at a time. The problem is also that she and John have diametrically opposite stupid ideas of how to deal with his being a very furry dog.