Dr. Juliane Kaminski of the University’s Dog Cognition Centre proved that the facial expressions dogs make are not a result of their emotions, but rather are a purposeful act to communicate. Her research also showed that dogs make more facial expressions when people are looking at them, further illustrating that dogs specifically use facial expressions to communicate to people. This finding further shows us that dogs make choices and decisions to purposely try to communicate with people.
One of the most common facial expressions that dogs made was to raise their brow. This facial expression often makes people feel that the dog is sad and is often referred to as the puppy dog look.
Of course, it must be understood that dogs use a whole realm of body language to communicate, not just their facial expressions. Keep in mind that dogs who have excessive facial hair may make it difficult, if not impossible for people to see the raised brow.