Clinical ethology—the study of animal behavior in a veterinary context—has shifted from a niche interest to a core component of general practice. This change is driven by the understanding that a "healthy" animal is not merely one free of disease, but one that is mentally stimulated and emotionally stable.

(e.g., animal rights in clinical trials)

We used to think that a "good patient" was one that froze in fear. We now know that fear shuts down the immune system. A terrified animal releases cortisol (the stress hormone), which actually slows wound healing and increases recovery time.

: Using behavioral indicators to assess the physical and psychological well-being of animals in shelters or farms. Comparative Psychology : Studying cognitive processes across different species. Behavioral Pharmacology