Dogs wag their tails more to the right when they feel happy or relaxed.
Other animals could exhibit similar interpretations. “We know that if a cockatoo looks with its left eye it’s more likely to attack than if it looks with its right eye. It may be that that other cockatoos know whether they’re being eyed off with a left eye, and keep away more.”
http://www.theaustralian.com.au/higher-education/left-leaning-dogs-peturb-fellow-pooches/story-e6frgcjx-1226750484140#sthash.vaOjv1xc.dpuf
Other animals could exhibit similar interpretations. “We know that if a cockatoo looks with its left eye it’s more likely to attack than if it looks with its right eye. It may be that that other cockatoos know whether they’re being eyed off with a left eye, and keep away more.”
http://www.theaustralian.com.au/higher-education/left-leaning-dogs-peturb-fellow-pooches/story-e6frgcjx-1226750484140#sthash.vaOjv1xc.dpuf