| Physical Condition | Behavioral Manifestation | | :--- | :--- | | Chronic pain (osteoarthritis) | Reduced activity, reluctance to jump, sleep disturbances, new-onset aggression when touched. | | Dental disease | Head shyness, dropping food, excessive salivation, irritability. | | Hyperthyroidism (cats) | Increased vocalization, restlessness, night waking, heightened aggression. | | Cognitive Dysfunction Syndrome (dogs) | Disorientation, altered social interactions (e.g., not greeting owners), house soiling, sleep-wake cycle reversal. | | Neurologic lesions | Circling, head pressing, sudden compulsive behaviors, loss of learned behaviors. |