How can a veterinarian determine if an animal is experiencing pain?

Veterinarians can determine whether an animal is experiencing pain primarily by observing changes in behavior, as animals often exhibit specific behavioral signs when in discomfort. These signs may include changes in appetite, alterations in usual activity levels, vocalizations, changes in grooming habits, or altered interactions with humans or other animals. Unlike humans, animals cannot verbally communicate their pain, so behavioral changes provide critical clues for veterinarians to assess their pain levels.

While heart rate fluctuations, temperature, and blood tests can provide additional information regarding an animal's health status, they are not direct indicators of pain. Heart rate may be affected by stress, excitement, or other health issues; temperature can indicate infection but not pain; and blood tests may show changes in physiological conditions but do not directly reflect an animal's experience of pain. Thus, behavior is the most reliable and immediate indicator veterinarians can observe to assess pain in animals.