At what age is a dog or cat considered a senior?

It depends on size. AAHA classifies large/giant breed dogs as senior at 6, medium dogs at 8, and small dogs at 10. Cats are classified as senior at age 11 by the AAFP, though age-related changes often begin around 7-8.

How often should senior pets visit the vet?

Twice a year. The AAHA and AAFP both recommend biannual wellness exams for senior pets. Blood work, urinalysis, and blood pressure checks catch problems like kidney disease, diabetes, and hypertension before symptoms become obvious.

What are the most common health issues in senior pets?

Osteoarthritis, kidney disease, dental disease, hyperthyroidism (cats), diabetes, and cognitive dysfunction syndrome. The AVMA notes that most of these are manageable when caught early but devastating when found late.

Should I change my senior pet's diet?

Yes, typically. Senior pets often need diets with adjusted protein levels, fewer calories, and joint-supporting supplements like glucosamine. Your vet can recommend specific formulations based on blood work results.

Senior Pet Care: What to Know After Age 7

When "Senior" Actually Starts

The American Animal Hospital Association (AAHA) doesn't use a one-size-fits-all threshold. Large and giant breed dogs — Great Danes, Saint Bernards, Mastiffs — are classified as senior at 6 years old. Medium breeds hit that mark at 8. Small breeds don't cross the line until 10. Cats get their own timeline: the American Association of Feline Practitioners (AAFP) calls them senior at 11, though most vets start watching for age-related changes around 7 or 8.

These aren't arbitrary numbers. They reflect documented differences in when breed-specific and size-specific health conditions tend to appear. A 6-year-old Great Dane is statistically more likely to have early-stage osteoarthritis than a 6-year-old Beagle.

The Twice-Yearly Rule

Both AAHA and AAFP recommend biannual wellness exams for senior pets. That's every six months, not once a year. The reason is simple: a lot can change in a year. A cat that was fine at last year's checkup may now have early kidney disease detectable only through urinalysis and blood chemistry. A dog's arthritis may have progressed from mild to moderate, visible on X-ray but not yet obvious in gait changes.

These visits should include complete blood count, blood chemistry panel, thyroid screening (especially for cats), urinalysis, blood pressure measurement, and a dental assessment. The American Veterinary Medical Association (AVMA) considers these baseline diagnostics essential for senior pets.

The Big Five: Common Senior Conditions

Osteoarthritis. The most common age-related condition in dogs. The AVMA estimates that roughly 90% of cats over age 12 and 25% of dogs over 1 show radiographic evidence of arthritis. In cats, the signs are subtle — sleeping in warmer spots, skipping the counter jump, reduced grooming. In dogs, look for stiffness after rest, reluctance on stairs, or lagging on walks.

Kidney disease. Chronic kidney disease (CKD) is the leading cause of death in senior cats. The International Renal Interest Society (IRIS) staging system helps vets categorize CKD progression. Early detection through urinalysis can add months or years to a cat's life with dietary management.

Dental disease. Tooth resorption affects up to 60% of cats over age 6 (AAFP). Periodontal disease is the most common condition in dogs over 3 (AVMA). Neither gets better on its own — both cause chronic pain that pets hide instinctively.

Hyperthyroidism. The most common endocrine disorder in cats over 10. Symptoms include weight loss despite increased appetite, increased thirst, and hyperactivity. Blood testing catches it easily; treatment options include daily medication, radioactive iodine therapy, or prescription diets.

Cognitive dysfunction syndrome (CDS). Essentially dementia in pets. Signs include disorientation, altered sleep cycles, house soiling in previously trained animals, and reduced social interaction. It's underdiagnosed because many owners attribute the changes to normal aging.

Diet and Weight Management

Senior pets generally need fewer calories and sometimes adjusted protein levels. The Association of American Feed Control Officials (AAFCO) defines "senior" nutrient profiles, though the specifics vary by species and health status. Overweight pets live shorter lives — a Purina study found that lean-fed dogs lived 1.8 years longer than their overfed counterparts.

Joint-supporting supplements like glucosamine and omega-3 fatty acids have modest evidence behind them. They won't reverse arthritis, but some studies show measurable improvement in mobility scores. Ask your vet before starting supplements — some interact with medications.

Adapting Your Home

Ramps for furniture access. Non-slip rugs on hardwood floors. Litter boxes with low entry sides for arthritic cats. Heated beds for joints that ache in cold weather. Water bowls on every floor so your pet doesn't have to navigate stairs for a drink. These small changes add up. They don't cure anything, but they remove barriers that make daily life harder for a body that's losing capacity.