A pet who looks fine can still be hiding something. Cats and dogs are good at covering up discomfort, and many age-related problems start slowly. That is why vets and welfare groups ask for check-ups to become more frequent as pets get older.
Pick your pet below. The planner shows how often the vet guidance suggests a check-up, and builds a short list of changes to tell the vet about.
Tick anything that has changed. You are not diagnosing, just collecting notes for the vet.
There is no single birthday. The 2021 AAHA/AAFP cat guidelines call cats senior from about 10. For dogs it depends on size, because big dogs age faster. The American Kennel Club says small breeds are often seen as seniors from around 8 to 12, while giant breeds may reach it at 6 or 7. Vets often use the last quarter of the expected lifespan as a rule of thumb, and sources do not agree on one age. So the planner gives a starting point, not a verdict.
The vet will usually weigh your pet, look at the mouth and teeth, listen to the heart, feel the joints and belly, and ask about eating, drinking and moving around. They may suggest blood or urine tests to look at things like the kidneys and liver. Your notes help a lot here, because a pet often behaves differently in the clinic than at home.
A change is never "just old age" until a vet has said so.
A check-up schedule is a minimum. Call your vet sooner if your pet suddenly drinks or pees much more, stops eating, loses weight, has trouble breathing, cries out in pain, or seems confused. This guide cannot tell you what a change means. Only a vet can.
Bring your notes, a short video of anything that comes and goes (like limping), and a list of any food, supplements or treatments your pet gets. Give a cat time to get used to the carrier, and reward calm behaviour with treats. Never give your pet human medicines, and never change medicines or diet for a sick pet without asking the vet first.