In the novel Mrs McGinty's Dead, Piggy is a pig owned by Johnnie and Maureen Summerhayes.
Maureen mentions to Robin Upward that they had had a "terrible fright" about Piggy one day, as he was lying down, and did not want his breakfast. They had read up all the diseases in the Pig Book, and could not sleep because they were so worried about him. However, the next morning, Piggy was "frightfully well and gay". When Johnnie came to feed him, Piggy charged at him, and knocked him flat.