There are scads and scads of picture books about new baby jealousy. A Baby Sister for Frances, Julius, the Baby of the World, Peter's Chair, and When the New Baby Comes, I'm Moving Out come immediately to mind. And there are tons of others, with good reason. The entry of a new baby into a family is an event with dramatic and lifelong consequences for the until-then only (or youngest) child.
However, there's a subgenre of picture books about pets jealous of a new baby. And one of them was written by none other than Madeline L'Engle and illustrated by one of my favorite illustrators, Christine Davenier! Even among this subgenre, though, L'Engle's book has a twist. The dog at issue believes the new baby is also a dog, simply one of an inferior breed, one which is not house-trained and which gets to be carried everywhere. While the aptly named The Other Dog is not of the same quality of L'Engle's other works, it is worth seeking out by dog lovers, parents of older-siblings-to-be, and picture-book-collectors.
Other picture books about pets jealous of a new baby include Bittle and McDuff and the Baby. Do you know of any others?