In short, ignoring behavior leads to inaccurate lab results, iatrogenic injury, and a chronic state of ill health for the anxious patient.
Research in this area has shown that reducing stress during exams leads to more accurate vital signs (a stressed cat has an artificially elevated heart rate and blood pressure) and faster healing post-surgery. Chronic stress elevates cortisol, which suppresses the immune system. By managing behavior, veterinary science directly boosts physiological recovery.