Edwin Giesbers / Orang utan (Pongo pygmaeus) close-up of mouth of dominant male called Aman. Matang wildlife centre, Sarawak, Borneo, Malaysia, June 2010. Endangered

Petra Wegner / Pug lying on a rug next to a mixed breed dog with their chins on the floor.

Jane Burton / Yellow and Chocolate Labrador Retriever pups lying down with chins on the floor.

Jane Burton / Yellow and Chocolate Labrador Retriever pups lying down together, chins on the floor

Jane Burton / Two Brittany Spaniel pups asleep with chins on floor.