image of a German Shepherd puppy next to an adult dog

What’s the Difference Between Puppy and Adult Dog Food?

Growing puppies have different nutritional requirements than adult dogs, and puppy food reflects these needs. Eating adult food won't hurt a puppy in the short term, but they need a nutritionally appropriate diet to develop a healthy brain and body and to live a healthy life.

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One of the most common questions asked by first-time dog owners is “what’s the difference between puppy and adult dog food?” Why exactly do puppies need different types of food from their grown-up counterparts, and what are the dangers if your puppy is eating an older dog’s food? 

We’ll break down why dogs need different types of food during different stages of life in this guide.

In this guide:

Why do Puppies and Adult Dogs Need Different Food?

They’re all dogs. It all goes down the same way. Why do they even need different food? 

If you’re having a hard time understanding why puppies need a different diet than adult dogs, just think of humans. Would you feed a newborn baby a steak dinner with chips and salad? (If you answered “yes,” then parenting probably isn’t for you.)

Puppies have different dietary needs than adult dogs, just as human babies do compared to adults. At this life stage, parts of a puppy’s body and brain are still developing, and the food they eat needs to reflect these particular requirements.

Puppies have small stomachs, but big caloric needs, so how much energy is packed into each mouthful is important. Whether it’s wet food or dry food, the fat and protein content, and the caloric density of different portion sizes all matter.

For toy breeds, such as Yorkshire Terriers, getting a small-breed puppy food is also important, as these little pups will have a hard time getting their teeth around big pieces of kibble that larger breeds could easily eat.

>> Read more: Best Dog Food for Yorkies

Puppy food vs adult food: the question of protein

Protein is one of the three primary macronutrients (major nutrient types) alongside carbohydrates and fats. Protein provides the building blocks for muscle growth and physical development; with that in mind, it’s hardly surprising that puppies—little, growing bundles of energy—require more protein in their diet than fully-matured dogs. 

How much protein do puppies need?

Puppies are generally advised to get between 22% and 32% of their daily food intake from protein, whereas adult dogs only need around 18% of their daily calorie content to be protein-based. This higher protein consumption supports puppies throughout this growth-driven period of their lives.

>> Read more: Open Farm Dog Food Review

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Amino Acids

It’s not enough for a puppy food to simply “contain protein.” The word protein refers to many different types of protein, built from chemicals called amino acids; these different amino acids help puppies develop in different ways and areas, and so it’s also important that puppy food contains a wide-ranging variety of proteins. 

There are ten major amino acids your puppy food should contain, these are: 

  • valine 
  • threonine
  • tryptophan
  • phenylalanine
  • lysine
  • methionine
  • leucine
  • isoleucine
  • arginine
  • histidine

Other major differences between puppy and adult food

Although varying protein levels might be the primary difference between puppy and adult dog foods, it’s far from the only one.

We’ve touched briefly on the idea of caloric density—how much energy a piece of food packs in each bite. In addition to protein, the more fat-dense a food is, the more energy you’ll typically get from each piece of food. That’s why puppy food generally has a higher fat content than adult or senior dog food, and it often includes specific fatty acids.

This higher fat content doesn’t just help a puppy grow; it’s more practical for them, too. Puppies have much smaller stomachs than adult dogs, so getting all of the energy they need to comfortably fit into their stomachs is a challenge unless you use nutritionally-dense food!

As a general rule, puppies tend to require almost double the number of calories they’ll need as an adult (and sometimes more). And all of that food has to fit into a much smaller stomach! You can see, then, why packing those calories into dense little tidbits of dry food is so important.

These differences are also why adult dogs shouldn’t eat puppy food. Aside from leading to excessive weight gain, the extra protein and fat content could cause stomach upset.

Can puppies eat adult dog food?

Yes and no. Feeding your puppy a little adult dog food shouldn’t do them any explicit harm. But at the same time, if they regularly eat an adult formula, they probably won’t have the optimal, balanced diet they need to maintain their rate of growth.

If you think about the earlier question of protein, for instance, adult dog food contains less protein than puppy food, and senior food has still even less. So, if you were to consistently feed your puppy regular dog food, they would consume a significantly lower quantity of protein over time, which in turn could lead to joint issues and affect their energy levels and their adult height and weight.

The food itself isn’t bad for the puppy per se. It’s simply not giving the dog everything they ideally need to maintain a healthy weight and develop into a healthy adult.

>> Read more: Hungry Bark Dog Food Review

When can puppies eat adult dog food?

Puppies can usually start eating adult maintenance food between 6 to 12 months of age. But the exact timing will vary by dog. As long as your dog is showing signs of rapid growth and development, they should remain on a puppy formula. However, once the growth levels off, they can be transitioned onto an adult diet.

This timing often coincides with your dog’s spaying or neutering procedure, which will reduce their energy requirements. However, if your dog is spayed or neutered before this age, you may want to keep them on a puppy diet for a few months longer. Just ask your vet when you visit for the procedure.

If you’re already a dog owner, and you’ve just added a young puppy to your pack, you may be tempted to stick both dogs on the same pet food. While this may be a practical solution later on, don’t do it just yet.

If you’re still feeding your dog the food they were given by the shelter or breeder, but it’s time to transition them to an adult formula, now is also an excellent time to upgrade their food to a more nutritious diet. If you take nutrition very seriously, check out a fresh food subscription brand such as Just Food for Dogs or The Farmer’s Dog. If you prefer dry food, try out Spot & Tango’s UnKibble line or at least a clean brand that doesn’t use meat meals, such as Halo.

Halo’s Holistic Chicken & Chicken Liver Recipe

  • Only whole meat: no meat meals or byproducts
  • Certified Sustainable: made in the U.S. in partnership with the Global Animal Partnership (GAP). Sourced from cage-free farms.
  • No GMOs: only whole, natural fruits and veggies

How to stop a puppy from eating older dog’s food.

Many puppies are ravenous, not to mention curious, eaters. So it’s not surprising that a hungry pup may dig into their older sibling’s bowl as occasion allows. But for the reasons explained above, you shouldn’t allow it often.

If your puppy is eating an older dog’s food often, you need to rethink your feeding structure. While free-feeding works well for single dogs with healthy eating habits, it’s not right for all situations.

Over the next few days, transition your dogs to a timed feeding schedule. This means they should eat at relatively the same time each morning and evening (and afternoon, in the puppy’s case). However, they should eat separately, and they should only have a few minutes to do it.

You should keep your dogs’ food bowls in a room with a door or a doggy gate that will keep them separate. If this isn’t possible, you’ll have to crate the pup or hold them while the older dog eats.

Feed your older dog first. Put the food in the bowl and call them over to eat. If they eat the food promptly, great. But if they don’t, wait three to five minutes before putting their food back in its storage container. Return the empty bowl to the floor so they can see that it’s gone.

This may seem harsh, but you need to train your dogs to eat while the food is available and understand that it won’t always be there. If the older dog doesn’t eat anything during the first attempt, they’ll probably gobble down their dinner. If they hold out even longer, you can slip them a small snack (by hand, not from their bowl!) to tide them over. But don’t feed them a full portion. The only way they’ll learn is by spending a few hungry hours wishing they’d eaten when they had the chance.

After the adult dog has eaten, allow the puppy into the room and repeat the process with their own food

After a few days of this rigid training, both dogs should fall into a feeding routine that has them eating their own food promptly and moving on with their day. Eventually, you may even be able to resume feeding them at the same time.

>> Read more: Dog Won’t Eat After Surgery? How & What to Feed a Dog

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