Suddenly, it's all about death.

Of course, Mary. It's all for his sake.
Listen, when did Mary Worth start getting so heavy? All this grandstanding about helping out animals is really a lead-in to worries about one's own mortality? Typical Mary to passive-aggressively project her anxiety onto someone else, in this case Chester. Notice how Toby leans in significantly to murmur about the fliers, so Chester won't hear. She doesn't need to, because Chester is busy . . . flying? Allergic? Getting stung by a bee that's on the roses? Anyway, he's busy, plus a dog, and not concerned with what Mary's up to: preparing for death!

She's been making her argument for weeks now: Animals help people live longer and keep them healthy. What's clearly on her mind is her own health and longevity. Is Mary sick? (What do people in Mary's world get sick with, anyway? Rickets? Sometimes they are drawn as if they have rickets. I don't know that anyone in the strip has ever had a disease. Even the Vietnamese orphans, in their brief and bizarre appearance, smiled from their beds.) Mary would be the first one ever to succumb to illness . . . and her only hope is Chester!

You know what this means, right? Mary is desperate. Toby's the instigator and the only one who knows that he's not really Mary's dog. Check out Mary's crossed arms and her look of deranged determination in the last panel. Something terrible is going to befall Toby!
Possible outcomes:
-Toby drowns in the Charterstone pool
-Toby falls off a horse
-Professor Cameron finds Toby dead with dog bites on her. He blames werewolves. Bolstered by more unnatural phenomena, the psychic neighbor makes a comeback
-Mary offs Toby, then finds out that Dr. Jeff Cory lied when he diagnosed her. Dr. Jeff Cory defends himself, saying that he lied to get Mary to break her vow of chastity. Everyone has a good laugh and goes for a drink at the Bum Boat