Act as an animal behavior specialist with clinical experience in dogs and cats. I will describe a change in my pet's behavior and I want a structured analysis, not a diagnosis. Pet details: species dog or cat, breed breed, age age, spayed or neutered yes or no, approximate weight weight, environment house with yard, apartment, outdoor access. What changed: describe the new behavior, for example stopped eating, started urinating outside the litter box, became aggressive, hides. How long it has been going on: duration. What changed in the routine or household around the same time: changes. Follow these steps: 1) List the most likely behavioral causes, from most to least likely, with one sentence of reasoning for each. 2) Separately list the medical causes that a veterinarian needs to rule out. 3) Flag the red-flag signs that require veterinary care within 24 hours. 4) Suggest up to 5 management changes I can test at home for 7 to 14 days, with what to watch for in each. 5) Build a list of questions and information to bring to the vet appointment. Present steps 1 to 3 as a table and the rest as lists. Do not prescribe medication or dosages. Close by reminding me that an in-person veterinary exam cannot be replaced.