Senior dog nutrition guide: feeding your aging dog well

February 6, 2026

My neighbor's Golden Retriever turned 10 last year, and she asked me if she should switch to "senior" food. It's a common question, and the answer is less straightforward than the pet food industry makes it seem. There's no AAFCO definition for "senior" dog food. Any manufacturer can slap that label on a bag without meeting any specific nutritional standard beyond the basic adult maintenance requirements.

That doesn't mean older dogs have the same nutritional needs as younger ones. They don't. But the changes are more nuanced than "buy the bag that says senior."

When does a dog become "senior"?

It depends on size. Small breeds (under 20 pounds) are generally considered senior around 10-12 years. Medium breeds (20-50 pounds) hit that threshold at 8-10 years. Large breeds (50-90 pounds) at 7-8 years. Giant breeds (over 90 pounds) can be considered senior as early as 5-6 years.

These are rough guidelines. Individual aging varies enormously. I've seen 12-year-old Border Collies that act like puppies and 7-year-old Bulldogs that are clearly slowing down. Your vet can help you assess where your specific dog falls based on their health markers, not just their birthday.

What actually changes with age

Several things shift as dogs get older, and they all affect nutrition:

Metabolism slows down. Senior dogs need about 20-30% fewer calories than they did in middle age, assuming their activity level has also decreased. This is the single biggest dietary change for most aging dogs. If you keep feeding the same amount, they gain weight. And excess weight in an older dog accelerates joint deterioration, increases cancer risk, and shortens lifespan.

Muscle mass decreases. Sarcopenia (age-related muscle loss) happens in dogs just like in humans. A 2011 study published in the Journal of Veterinary Internal Medicine found that senior dogs lost muscle mass even when maintained at stable body weight. The practical implication: older dogs may actually need more protein, not less, to maintain muscle.

This contradicts a common misconception. For decades, vets and pet food companies recommended reducing protein for senior dogs to "protect the kidneys." Research has consistently shown that protein restriction doesn't prevent kidney disease in healthy dogs. A healthy senior dog benefits from moderate to high protein (25-30% on a dry matter basis) to counteract muscle loss. Dogs with diagnosed kidney disease are a different story and need a specific therapeutic diet prescribed by their vet.

Digestive efficiency declines. Older dogs absorb nutrients less efficiently. Their gut bacteria change, and digestive enzyme production can decrease. This means the quality of ingredients matters more, not less, as dogs age. Highly digestible protein sources and added prebiotics or probiotics can help.

Dental health deteriorates. By some estimates, 80% of dogs show signs of periodontal disease by age three. By the time they're seniors, dental issues can directly affect eating. Dogs with painful teeth may eat less, chew less thoroughly, or avoid harder foods. This is one practical reason some owners switch seniors to wet food or softened kibble.

Calories: getting the amount right

This is where most people go wrong with senior dogs. The dog slowly gets less active, but the feeding amount stays the same. Over months, they put on a few pounds. It's gradual enough that you don't notice until the vet mentions it.

Weigh your senior dog regularly (monthly is good). If they're gaining weight on their current food, reduce portions by 10% and reassess in two weeks. Don't cut more than that at once. Gradual reduction is easier on them and gives you time to see the effect.

If your dog is losing weight unexpectedly, that's a vet visit. Unintended weight loss in a senior dog can indicate thyroid problems, kidney disease, cancer, or dental pain. Don't just increase the food without investigating why they're losing weight.

Supplements worth considering

Joint support comes up a lot for senior dogs. Glucosamine and chondroitin have moderate evidence for reducing arthritis symptoms. Fish oil (EPA and DHA omega-3 fatty acids) has stronger evidence for reducing joint inflammation, with a 2010 study in the Journal of the American Veterinary Medical Association showing improved mobility in arthritic dogs given fish oil supplements.

Fiber can help senior dogs with constipation, which becomes more common with age and reduced activity. Pumpkin puree (plain, not the pie filling) is a simple addition at about a tablespoon per 20 pounds of body weight.

Antioxidants (vitamins E and C, along with beta-carotene) show up in many senior dog foods. The research on cognitive benefits in dogs is limited but slightly positive. A 2002 Purina study found that senior dogs fed antioxidant-enriched diets performed better on cognitive tests than control groups.

Don't add supplements without checking with your vet first. Some supplements interact with medications, and fat-soluble vitamins can accumulate to toxic levels.

Feeding schedule adjustments

Younger adult dogs do fine on one or two meals per day. Senior dogs often benefit from splitting their daily food into two or three smaller meals. Smaller meals are easier to digest and help maintain more stable blood sugar levels throughout the day.

If your senior dog has become a picky eater (common, especially with dental issues or reduced sense of smell), try warming the food slightly. Warm food releases more aroma, and smell drives appetite in dogs more than taste does. Adding a small amount of low-sodium broth to kibble can also increase interest.

Elevated food bowls help dogs with arthritis or neck pain eat more comfortably. This is a simple change that makes a noticeable difference for many older dogs.

Should you buy "senior" dog food?

Some senior-labeled foods are genuinely well-formulated for older dogs: moderate calories, higher protein relative to calories, added joint support, digestible ingredients. Others are just regular adult food with different packaging.

Instead of going by the label, compare the actual guaranteed analysis. Look for:

• Lower calorie density (under 350 kcal/cup for most senior dogs)
• Protein at 25% or higher on a dry matter basis
• Named animal protein as the first ingredient
• Added omega-3 fatty acids from fish oil
• Moderate fat (8-12% on dry matter basis, lower than adult maintenance)

A regular adult food that meets these criteria works just as well as one labeled "senior." The label doesn't guarantee the formulation is appropriate.

The short version

Feed less as activity decreases. Keep protein moderate to high unless your vet says otherwise for a specific medical reason. Weigh your dog regularly. Consider joint supplements if they're showing stiffness. Split meals into smaller portions. And don't assume "senior" on the label means the food is right for your dog. Read the actual numbers.

Growing old is hard enough without being hungry on top of it. Get the portions right, keep the quality up, and your senior dog will thank you by sticking around a bit longer.