Bernese Mountain Dog adult and puppy

The Difference Between Puppy & Adult Dog Food

Written By Vedrana Nikolic | Canine Coach, B.A Ethnology & Anthropology, M.A Semiotics.
Edited & Fact Checked By Renae Soppe | B.A Journalism & Science. 
Last Updated: 5th January 2024

With so many brands and recipes filling up the pet food aisle, choosing the right dog food is a difficult task.

But for a responsible pet parent like you, that’s not even the end of your concerns. You still need to choose the right formula for your dog’s life stage. Or do you?

We’ve asked a team of experts to unravel the mystery. Does it matter which recipe you get for your dog, and why? Let’s find out.

Related: The Best Dog Food Australia.
Related: How To Choose The Right Dog Food?
Related: How Is Australia’s Dog Food Industry Regulated?
Related: What is AAFCO? The Association of American Feed Control Officials.
Related: What Is the Pet Food Industry Association of Australia (PFIAA)?
Related: AAFCO vs PFIAA: Dog Food Standards Comparison Australia.

Related: Understanding Guaranteed Analysis Levels in Dog Food.

Differences In Nutritional Requirements Between Puppies And Adult Dogs

Puppy and adult dog food formulas are indeed different, due to their distinct nutritional requirements at different life stages. Puppies grow like weeds. One day, they can fit in the palm of your hand, but soon enough they’re already too big to sit in your lap. Their fast growth puts special demands on their young bodies, and those demands must be met by the nutrients they intake.

Related: Can Puppies Eat Adult Dog Food?

Once dogs reach adulthood, their metabolisms slow down and their nutritional requirements change. But what exactly is the difference in dietary needs between puppies and adult dogs? A couple of things, actually.

Protein Content

Proteins are often called the “building blocks of life” since they’re essential for body development and functioning. Among other things, they’re required for:

  • Building and repairing muscles and tissue
  • Growing hair
  • Creating hormones and enzymes
  • Promoting immune system
  • Producing energy

Throughout puppyhood, a dog’s body is developing, so it needs a lot of protein to keep all the aforementioned body functions working properly. However, proteins can’t be stored in a dog’s body like fats or carbs, which means they have to be supplied through an everyday diet.

Related: How Much Protein Is In Dog Food?

For that reason, puppy dog food is packed with protein. Exactly how much protein it may have varies between brands and formulas. The Association of American Feed Control Officials (AAFCO) recommends that the daily requirements for puppy diets should contain at least 22% dry matter (1).

Related: Understanding Dry Matter In Dog Food.

And yes, even though AAFCO is an American organisation, its pet food standards are recognised globally. In fact, the Pet Food Industry Association of Australia (PFIAA) encourages Aussie manufacturers to follow the standards set by AAFCO.

So, what does AAFCO say about adult dogs? Once they stop growing, dogs don’t require as much protein in their diet. For an adult with an average activity level, the lower limit of protein content should be 18%.

The 4% difference may not seem like much on paper. However, feeding puppies adult food for a prolonged time will deprive them of the necessary proteins and may cause developmental issues. On the other hand, feeding adult pooches with protein-packed puppy food can cause them to grow, but only sideways, which you surely don’t want.

Fat Content

Even though fat usually gets a bad reputation, it’s another essential nutrient in dog food. In fact, fat is the primary source a dog’s body relies on to provide energy. To put this into perspective, a gram of fat supplies more than twice as much metabolisable energy as either protein or carbohydrate (2).

Aside from being the main fuel, fat also improves the absorption of vitamins A, D, E and K. While all of these vitamins are necessary for a dog’s health, vitamins A and D are particularly important for growing puppies. Vitamin A, also known as retinol, aids in growth and neurological development. Vitamin D, on the other hand, helps with the absorption of calcium and phosphorus, which are necessary for maintaining healthy bones and muscles.

Unlike protein, excess fat doesn’t get flushed by the dog’s body. Instead, it’s deposited under the skin for later. In theory, this is quite practical. However, dogs that don’t regularly burn off the energy they get from their fat intake will eventually gain weight.

When they’re not sleeping, puppies are definitely making sure they spend every drop of energy they have. Adult dogs are generally not like that. Aside from some boisterous breeds like Border Collies and Huskies, most grown-up pooches spend a good portion of their day just chilling. For such a leisurely lifestyle, fat-heavy puppy food is a bit too much.

AAFCO’s nutrient guidelines recommend a minimum crude fat level of 5.5% for adult dogs and 8.5% for puppies. Of course, the actual numbers are somewhat higher. A fat content between 8% and 15% would be ideal for adult pooches, while the little ones could benefit from food with fat levels between 10% and 25% (3).


DHA is an essential fatty acid that helps with the neurodevelopment of puppies. While nursing, the puppies get their daily dose of DHA through the mother’s milk. But once they’re weaned, they need to get it from their diet.

This fatty acid is beneficial to adult dogs as well due to its anti-inflammatory properties. Still, the impact it has isn’t significant enough to make it a staple in adult dog food formulas. They are, however, often included in puppy recipes to aid in healthy growth.

Special Considerations For Large Breed Puppies

While small and medium-sized dogs reach their full size within a year or so, large breeds grow up to 24 months. Regardless, they grow at a much faster rate compared to their smaller cousins. Let’s take a Great Dane puppy as an example. One month old, this small creature is just two kilograms heavy. Fast forward six months, and it may weigh the same as you.

Related: The Best Puppy Food Australia.

Obviously, such fast growth puts joints and bones under a lot of stress. That’s why it’s important to keep a large pup’s weight under control to avoid the risk of hip and elbow dysplasia. For that reason, large-breed puppy formulas have less protein and fat content compared to recipes intended for smaller puppies. Still, they’re different from adult formulas due to different levels of minerals and vitamins.

When & How To Switch From Puppy To Adult Dog Food

Since there are different formulas for different life stages, a question naturally pops up: when and how to transition?

Related: When To Switch Your Puppy To Adult Dog Food?
Related: What To Feed Puppies In Their First 6 Weeks?
Related: What To Feed A Puppy At 8 Weeks Old?

For small and medium-breed puppies, adulthood begins somewhere around one year of age. By this time, their growth plates are closed and they have reached their final size. As for large breeds, they’re generally not considered mature until they’re 18 to 24 months old. Until then, they should be fed puppy dog food intended for their size.

Of course, you don’t just abruptly decide one day your dog is no longer a pup and start serving adult kibble instead. Switching food so suddenly can cause gastrointestinal issues, such as diarrhoea and vomiting. To avoid that, you should slowly introduce new food (4). A good transition looks something like this:

  • Day 1: 25% new food, 75% old food
  • Day 3: 50% new food, 50% old food
  • Day 5: 75% new food, 25% old food
  • Day 7: 100% new food

Taking things slow is key to success. However, if your dog experiences gut issues during the transition, proceed even more slowly. If the problem persists, maybe it's time to try another recipe.

My Final Thoughts

Understanding the differences between puppy and adult dog food is crucial for providing optimal nutrition for your furry companion at different stages of their lives. Puppy food is simply too caloric for most grown-up pooches, while adult dog formula lacks the necessary nutrients for the proper growth of puppies.


  1. Tupler, T. February 1, 2021. “Dog Nutrition: Guide to Dog Food Nutrients”. PetMD. Retrieved September 9, 2023.
  2. Eskew, S. April 1, 1999. “Fat, Protein and Carb Levels in Dog Food”. Whole Dog Journal. Retrieved September 9, 2023.
  3. Youens, L. October 13, 2022. “How much fat do dogs actually need in their diet?”. VetHelpDirect. Retrieved September 9, 2023.
  4. AKC Staff. March 2, 2022. “How to Switch & Transition Dog Foods”. American Kennel Club. Retrieved September 9, 2023.

Vedrana Nikolic

Vedrana Nikolić is Gentle Dog Trainers Canine Coach, Professional Writer, Anthropologist & dog lover.

With a Masters Degree in Semiotics & Bachelors Degree in Anthropology, studying the communication between animals and humans, Vedrana is able to use her expertise to analyse and review dog products and write informative posts on canine behaviour and training.

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