Panel 1: We start off with Farley reacting positively when for once, the Loud Angry THING makes happy sounding noises: "Wanna go out, Farl? Wanna go car ride? Wanna go downtown? Wanna remind people that Lynn has an idiosyncratic way of writing 'Hmmm?'"
Panel 2: As Farley BOUNDS into the back part of the station wagon, Elly gets all sappy sounding about how he's going to the Puppy Parlour to get prettied up.
Panel 3: This cheery, upbeat tone continues when she tells Farley that he's a good boy abnd a lucky doggie. This turns out to be a mistake.
Panel 4: This is because Farley balks when they get to the grooming salon because Loud Angry Creature only ever sounds like a friend when it wants to hurt him and put him in the scary place of sharp things. As he resists being forced into what he thinks is another round at the vet, Angry Elly thought-bubbles that Farley is smarter than he looks.
Summary: While it is rather obvious that he's a short guy in a dog suit again today, the fact of the matter is that Elly has proven herself to not be his friend no matter how friendly her tone of voice might be at any given time. Farley's brain can't help but associate Shouting Monstrosity with discomfort and being hollered at for no reason.