The age at which your puppy becomes an adult dog will depend on its breed and size. All breeds are categorised into five sizes of dog: x-small, small, medium, large, and giant. 

Your puppy will become an adult dog at the following ages:  
• X-small breed (4kg): eight months  
• Small breed (5 - 10 kg): 10 months  
• Medium breed (11 - 25kg): 12 months  
• Large breed (26 - 44kg): 15 to 18 months  
• Giant breed (45kg and up): 18 to 24 months  

The different classifications of when your puppy is an ‘adult dog’ are due to the length of the growth phase for different-sized breeds; large and giant dogs take a lot longer to fully mature than smaller dogs, although all of them have an intense growth spurt.    

Unique problems with puppies  Your puppy’s diet and care will need to take into account two specific problems which affect young dogs far more than adult dogs: their delicate digestive system and their reduced immunity.  

A puppy has a poorly developed digestive system than an adult dog, particularly immediately after they have been weaned, and it is easily upset by changes in environment or new foods. They need to be given a food which is the right size, shape, and texture to make it easy to eat, and highly digestible so they can get all the nutrients they need from it without it causing stomach upsets.  

Between the ages of four to 12 weeks, puppies enter a phase called the ‘immunity gap’. This is where their mother’s immune support, passed through her milk, is lessening but their own natural defences are not fully developed. During this time, their diet is a keyway to support this process and boost their immunity through nutrients like vitamin E. 

Check out Royal Canin puppy range that is that is tailored made for puppies of different breed and sizes.    

Changing from a puppy to an adult dog diet  Once your puppy reaches maturity, you can transition their diet and care, so you are making sure they get exactly what they need now they are fully grown.  Adult dogs need one to two meals a day, and a food which is nutritionally balanced to give them the energy they need without too much fat. You can transition to a new food gently by introducing it slowly over a week or two: mix it with their puppy food, gradually increasing the percentage of new food, so your dog gets used to it.