Which of the following indicates a horse is experiencing stress?

Pacing, sweating, and heavy breathing are all signs that indicate a horse is experiencing stress. When a horse exhibits these behaviors, it typically reflects its state of anxiety or discomfort. Pacing often shows that the horse is restless and trying to find relief from whatever is causing the stress. Sweating can be a physiological response to stress and indicates that the horse's body is reacting to undue pressure. Heavy breathing is another indicator of distress, signifying that the horse may be in a heightened state of alert or fear, which can occur in stressful situations.

In contrast, calm behavior and eating suggest that the horse is relaxed and content. Resting quietly in the barn is also a sign of comfort, indicating that the horse feels secure in its environment. Similarly, playing with other horses shows that the horse is likely feeling safe and can engage in social behaviors, which is typically associated with well-being rather than stress.