David Aretha 
When Dogs Smile [PDF ebook] 

Look at that happy dog: His mouth turns upward, his tongue hangs out, and his tail wags back and forth. That dog is smiling! Animal researchers have learned that dogs express numerous emotions, such as happiness, sadness, anxiety, fear, and compassion. When Dogs Smile explains how each emotion is expressed through physical manifestations. The book examines why a dog "smiles, " mopes, barks frantically, and licks the face of its crying owner. Quotes from experts and numerous color photographs help tell the story.