What physiological response is characterized by an increased heart rate due to stress?

The correct answer is characterized by an increased heart rate, which is referred to as tachycardia. This physiological response happens as part of the body's fight-or-flight mechanism triggered by stress. When an animal perceives a stressful situation, the sympathetic nervous system is activated, leading to the release of catecholamines like adrenaline. As a result, the heart beats faster to supply more blood—and, consequently, oxygen—to muscles and vital organs, preparing the animal to either confront the threat or flee from it.

Understanding this response is crucial in a veterinary context, as recognizing signs of tachycardia can help veterinary professionals address and manage stress in animals during examinations or treatments. Monitoring heart rate can guide practitioners in applying Fear Free techniques to reduce anxiety and improve the welfare of the animal in a clinical setting.