1) Trouble in Spades (2008) by Heather Webber, young adult mystery novel from HarperCollins, about landscaper and amateur detective Nina Quinn, featuring an unhousebreakable chihuahua.
2) Little Dot Finds a Home (2007) by Robert E. Brock, self-published booklet, children's tale of a chihuahua-corgi mix who loses her mama and litter mates but discovers she loves her new family. Illustrated with photographs.
3) Pippi Goes to the Doctor: Big Adventures of a Tiny Chihuahua (2009) by Colette Sowege, self-published booklet of photos for children's delight, limited to 100 signed/numbered copies.
4) Chiwo (2007) by Geraldine Solon. Children's book about Chiwo, an inhabitant of Chiville where only chihuahuas live. Chiwo's different from other residents of the town because he has five legs.