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When To Switch A Puppy To Adult Food | BetterVet

We Are What We Eat

Did you know that each life stage from a puppy, adult, or senior dog has different nutritional requirements? 

This is because different life stages have different energy needs. As pet parents, we can help support our puppy or dog’s wellness by feeding them top-quality diets. These diets help our dogs go through the functions of growth, repair, and refueling for their busy lives.

When a puppy is actively growing they need a higher density of calories and essential elements such as calcium and phosphorus to promote good bone growth. An adult is fully formed and only needs energy for maintenance and repair, so the quantity of calories needed is much less than a puppy diet. When a dog moves into their senior years, we can feed them a diet with a reduced amount of protein and salt, which are kinder on aging organs. Senior diets contain supplements like glucosamine and chondroitin, which can help soothe conditions like osteoarthritis.  

So, knowing when to switch a puppy to adult food is very important to your dog’s optimal health. If your adult dog stays on a puppy food diet for longer than needed, they can gain unnecessary weight very quickly. Make sure your pet is always at their ideal safe weight. If your puppy is changed to an adult diet too young, it can have effects on bone growth and strength. 

What Age Does a Puppy Become an Adult? 

A puppy transitions to becoming an adult somewhere between 8 months and 2 years old. 

  • Extra-small breeds like chihuahuas are adults at eight months

  • Small breeds like the Jack Russell Terrier are adults at ten months 

  • Medium breed dogs like the Collie are adults at twelve months 

  • Large breed dogs like Labrador Retrievers are adults at 14-16 months 

  • Giant breeds such as Newfoundlands are adults at 18-24 months 

Large and giant breed dogs take longer to mature as they have more growing to do. Their bones are still expanding and fusing right up until two years old. To support strong, healthy bones, they need controlled exercise schedules and a long time being fed puppy food. 

Changing to an adult diet also often coincides with the timing of spaying and neutering. This is usually done between 6 months and 2 years depending on your dog’s breed. The bigger the dog, the later the neutering surgery tends to be scheduled. After your pet is spayed or neutered,  their caloric needs are lower so an adult diet is more suited to their new metabolic needs. 

Which Adult Diet is Best? 

There are many brands of adult dog food, and the number of options can be overwhelming. With the introduction of grain-free, raw feeding, and home-cooked diets, it can be difficult to know what is best for your dog. As veterinarians, we always recommend feeding an adult dog a diet that complies with the AAFCO standards. This guarantees the food is to a minimum nutritional standard needed to keep an adult dog in good health. All commercial food companies will have the nutritional values of the food listed somewhere on the package. Learn more about pet foods and their labels on our blog. 

What if My Puppy Doesn’t Like Their New Food? 

When switching a puppy to adult food, you will need to gradually change over the food from the puppy variety to the adult mix. This increases the likelihood that they will continue to eat their new diet. Start by mixing a small amount of adult food into the puppy food and reducing the amount of puppy food. Over the next 7-10 days, slowly increase the proportion of adult dog food, and phase out the puppy food. By the end of the transition period, she should be on 100% adult dog food. 

Transitioning to the diet helps with acceptance, but also helps to avoid tummy upsets. Sometimes too much of a new food can cause diarrhea, loose stools, or flatulence. This is easily avoided by slowly introducing the new food over a week so the gastrointestinal system has time to adapt and adjust. 


How often should I feed my adult dog? 

You can feed an adult dog once or twice a day. Twice daily feeding can be more mentally stimulating for your dog and keeps them fuller for longer. It also reduces the chances of conditions such as bloat in large or giant breed dogs. 

What should I feed a pregnant dog? 

A pregnant adult female requires increased calorie intake in her last few weeks of pregnancy. It’s often easiest to feed puppy food in the last few weeks to accommodate these extra calorie needs but talk to a veterinarian for advice if unsure. 

What if my puppy won’t eat their new adult food? 

This can be a tricky one! They may truly not enjoy the flavor or texture, or you may have changed the diet over too quickly. Go back to basics and feed the old diet, but extend the transition period to the new diet out to two weeks. If at the end of this period they are still not interested in eating the new food, it’s worth trying another brand. 


Knowing when to switch a puppy to adult food is very important, and each breed will have a different time frame. If you are unsure, the best thing to do is to ask a veterinarian who can guide you on food brand selection, feeding amounts, and how to successfully change the diet from puppy food to an adult diet. Most dogs have no problem with diet changes, as long as they are done slowly. Occasionally some dogs, particularly fussy ones, may be harder to persuade, but most people have success with patience and perseverance. Changing your puppy to adult food benefits their health, and provides them with the correct calorie and nutrient requirements needed for the next stage of their lives.