"Half Moon" Eye... aka "Whale" Eye

The half-moon is defined by a large portion eye whites that accompanies a position known as avoidance, where the animal's head, and sometimes the body is turning away from a person, animal or object. The whites will resemble a crescent or half moon shape.

Half-moon eye is most often associated with stress, sometimes it is thought to be a precursor to a bite.

In either case, measures should be taken to alleviate the animal's stress before it is forced into a flight or flight response.