Which of the following is a sign of poor health in a horse?

Fast breathing in a horse can be an indicator of poor health. When a horse is in good health, its breathing rate should be calm and regular. An elevated respiratory rate, or fast breathing, can signal various issues, such as stress, pain, or respiratory conditions. It often indicates that the horse might be experiencing difficulties, such as a reaction to illness or distress, indicating that something is wrong with their overall health.

In contrast, a bright shiny coat typically signifies good health, good body condition reflects appropriate weight and health, and clear nostrils suggest that the horse is free from respiratory infections or allergies. All these signs are associated with a healthy animal, making fast breathing the clear outlier as a symptom of potential problems.