| Observed Behavior | Possible Underlying Medical Cause | |------------------|-------------------------------------| | Aggression in a previously friendly dog | Pain (arthritis, dental disease), hypothyroidism, brain tumor | | House-soiling in a cat | Urinary tract infection, kidney disease, diabetes, constipation | | Sudden fear or hiding | Vision or hearing loss, neurological disorder, chronic pain | | Pica (eating non-food items) | Anemia, nutritional deficiency, GI disease (e.g., IBD) | | Lethargy + aggression | Rabies (neurologic form), toxins, hepatic encephalopathy |