Having a puppy is such an exciting time! There is so much to think about, and so many decisions to make. Neutering, training classes, insurance, vaccinations – and of course, the big one – diet! What you feed your puppy can have a really important role in their growth and development, so it is important to get it right. But why is puppy food different to adult food, and when should you make the transition?

Why do puppies need different food?

When a puppy is young, they are growing really rapidly – much more so than humans at the same life stage. When you think about it, humans reach their adult size by about 18 years of age. Dogs reach their adult size in 9-24 months (depending on breed). So the growth happens over a much shorter time period. The average adult human grows to approximately 25-30 times their birth weight, but the average puppy eventually grows to 40-50 times their birth weight. So, not only does the growth happen over a much shorter time scale, but it is of a greater magnitude also. 

With this huge and rapid growth comes the potential for things to go wrong. And, the bigger the dog, the more potential there is for issues. If dogs grow too quickly, or too slowly, or if there is an imbalance in the nutrients that are needed for correct bone growth, then it can lead to joint problems, such as hip dysplasia (where the hip joints develop incorrectly, so the “ball and socket” joint does not fit together correctly); osteochondrosis (where some of the cartilage peels away from the underlying bone) or brittle bone disease. 

What does puppy food have that adult food doesn’t?

The 3 important factors that we need to control in a puppy’s diet are protein levels, energy levels and calcium:phosphorous ratio. 

Protein levels are important for muscle development. Energy levels (the amount of calories in the food) are important for overall growth. Too few calories will lead to impaired growth, but too many will lead to a growth rate that is too fast, and could predispose to joint problems or obesity. Calcium:phosphorous ratio is vitally important for correct bone development and should be between 1:1 and 1.8:1. This ratio being either too low or too high could lead to bone weakness or conformational problems. 

How do I know my puppy food is good enough?

First, look for accreditations. A good quality, commercial puppy food should be approved by the PFMA (Pet Food Manufacturers Association) Different rules apply in other countries; but in the UK, PFMA approval is generally a mark of a properly balanced and safe diet. This is the best way to ensure your dog food is completely balanced with all the correct nutrients. It will support your puppy to grow at the correct rate and ensure that their bones develop properly. But, once they have stopped growing and are no longer a puppy – this food will then be too high in energy and will start to make them overweight. 

Moving from puppy food to adult dog food

So, we are now back at the original question – when is the right time to switch your puppy from puppy food to adult food? Well, that all depends on when your puppy has reached their adult weight. This will vary from breed to breed. As a general rule, small breeds reach full growth much quicker than large breeds. Every dog will differ, and so it is important to monitor your own puppy’s growth in consultation with your vet, but as a general rule: 

  • Small breed (adult weight <10kg) dogs are fully grown at 9-12 months. 
  • Medium breeds (adult weight 10-25kg) get there at around 12-15 months.
  • Large breeds (adult weight 25-40kg) about 15-18 months.
  • Giant breeds (adult weight over 40kg) 21-24 months. 

It is a good idea to monitor your own puppy’s growth about every 2 months or so. You can do this using a growth chart, such as those provided by the waltham institute (can be downloaded here), and discuss with your vet if there’s anything unexpected (either growing too much or too little!). It is also a good idea to check with your vet when you suspect your puppy is fully grown and you are thinking of making the transition to adult food, just to make sure that they agree! 

Remember that a sudden change in diet can cause an upset stomach, so it is always a good idea to change your dogs food gradually. Start by adding small amounts of the new food in with the old, and then gradually increase the ratio of new food to old over the course of a week or two. Not only does this mean your dog will be less likely to have an upset stomach, but it also increases the chances of them accepting the new food easily and liking it, as they will barely notice that their old, familiar food has changed!

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