(Strip Number 579, Original Publication Date, 23 March 1984)
Panel 1: It's the morning of what's probably the day Mike has to return Humphrey; that being said, it's a fairly good thing that our lad tells John and Elly that he's managed to grab onto the little fellow.
Panel 2: As Elly gently pets the hamster, Mike tells her and John that he knew that he'd come out when he was hungry.
Panel 3: He then says that Humphrey had the best spot in the house....
Panel 4: Said spot is underneath Lizzie's highchair because of all the spilled food.
Summary: As karisu_sama says, Lynn has somehow confused a hamster with a dog. Watch the Lynnsight talk about how funny the image is rather than how inaccurate it is.