By studying behavior, veterinarians can diagnose internal ailments long before they show up on an X-ray. The Biological Basis of Behavior

In human medicine, a patient says, “My chest hurts.” In veterinary medicine, the patient says nothing. Instead, a dog hides under the bed. A cat stops using the litter box. A horse refuses to pick up a canter.

: Changes in behavior—such as lethargy, aggression, or a sudden lack of appetite—are often the first signs of underlying medical issues like pain, metabolic disease, or neurological disorders.