I assembled a Google AIY Vision Kit tonight (took about two hours). This will be great for the dog since it will allow the detection of humans and whether they are smiling. I am using the default mode--have not explored the many options at this time.

When no face is detected, the light on top is not illuminated.

When a face is detected (and it will easily detect a single face at a distance of 20 feet) the light turns blue.

When there is a smile, the light turns yellow. A big smile will turn the light bright yellow and trigger a piezo buzzer.