SpongeBob SquarePants (1999)

Season 4: Episode 13

While trying to beat a paddle-ball world record, SpongeBob forgets to feed Gary -- for 10 days. Gary runs away to downtown Bikini Bottom where he is taken in by a kindly old woman who confuses him with one of her many deceased pets. Once SpongeBob realizes that he has neglected Gary, he sets out in a town-wide search for him. Meanwhile, as Gary is wrapped in comfy blankets and indulged in an endless assortment of snacks, he discovers a very dark secret about this sweet old woman...