In veterinary science, behavior is often the first "vital sign." Because animals cannot verbalize pain, clinicians must rely on ethological markers. A cat that stops grooming or a dog that becomes uncharacteristically aggressive is often presenting a behavioral symptom of a physical ailment, such as dental pain or neurological dysfunction. By understanding species-specific behaviors, veterinarians can catch illnesses long before they show up on a blood test. Reducing "White Coat Syndrome"

In surgical contexts, the marriage of behavior and medicine is crucial for recovery.

Veterinarians use behavioral knowledge as a primary diagnostic tool. Because animals cannot communicate verbally, behavioral shifts—such as lethargy, aggression, or changes in grooming—often serve as the first clinical indicators of acute or chronic disease.