A dog is generally considered an adult when it has finished growing - and that point in time depends almost entirely on the breed's size. A small dog is often physically fully grown as early as around 8-12 months, a medium-sized dog typically at 12-15 months, while large and especially giant breeds only reach their adult body somewhere between 18 and 24 months. The question when is a dog an adult therefore does not have one fixed answer, and this is precisely why it is important to know your own dog's circumstances before you start treating it as an adult - both when it comes to exercise, training and, not least, feeding.
It is worth distinguishing between three forms of "adult", because they rarely coincide on the same day. Physical maturity is about bones and joints being fully developed. Sexual maturity often occurs earlier, already during puberty. And mental maturity - where the dog really settles down and appears composed - typically comes last and can be a long time coming, well into the second year of life. A dog can therefore easily look like an adult and still behave like a teenager for quite a while longer.
Why the breed's size determines when the dog is fully grown
Size is the single factor that matters most when assessing when a dog is an adult. A small breed simply has a shorter way to its adult weight and therefore finishes growing sooner. A large breed has to build up significantly more bone, muscle and mass, and that process takes longer. It makes good biological sense: the more body that needs to be formed, the longer the growth phase stretches out.
As a practical rule of thumb, small breeds such as the chihuahua, miniature dachshund and most terriers are often fully grown at around 8-12 months. Medium-sized breeds such as the cocker spaniel and border collie typically land somewhere between 12 and 15 months. Large breeds such as the labrador, German shepherd and golden retriever often take around 15-18 months to reach their full size, while giant breeds such as the Great Dane, Bernese mountain dog and Newfoundland can take up to 24 months to become fully adult. The figures are indicative, and there is individual variation within any breed, but they give a useful picture of when you can expect your dog to have finished growing.
Physical, sexual and mental maturity - three things that don't go hand in hand
The fact that a dog can reproduce does not mean it is an adult. Sexual maturity often occurs during puberty, long before bones and joints are finished, and a female dog can come into heat while she is still growing. It is therefore unwise to use sexual maturity as a guide for when the dog can be trained hard or fed as an adult.
Physical maturity is the one that matters most in everyday life. As long as the growth plates in the bones have not yet closed, the dog's skeleton is more vulnerable, and this is one of the reasons why you should be careful with long runs, repeated jumping and heavy strain, especially in large, young dogs. Mental maturity usually comes last. Many find that the dog physically resembles an adult but is still impulsive, playful and easily distracted - and that is completely normal. Calmness and self-control are things that mature over time and with experience, not something that switches on like a light on a birthday.
When should you switch from puppy meals to adult meals?
Feeding is where the transition from puppy to adult becomes concrete, and the timing closely follows the growth phase. A puppy has a higher need for energy and for the nutrients that support a growing body, and this is why puppy meals are composed differently from meals for adult dogs. If you switch too early, you risk giving a growing body too little of what it needs. If you switch too late, a fully grown dog may get more than it needs.
As a rule of thumb, small breeds switch to adult meals at around 10-12 months, medium-sized breeds at around 12 months, and large as well as giant breeds should stay on puppy meals longer - often to 18-24 months - precisely because they grow for a longer time. The transition should happen gradually over the course of a week, where you mix in a little more of the new meal at a time, so the stomach has time to get used to it. If you are unsure about the right time for your particular dog, ESSENTIAL FOODS' nutrition advisers are ready by phone, chat and email to help you get the switch right based on breed, size and development.
Meals for the adult dog - from puppy to life stage
When the dog is fully grown, the need changes from building up the body to maintaining it. The adult meals in the Adult collection are prepared for exactly that phase, where the dog needs to be kept in good shape, at a healthy weight and thriving well throughout the years as an adult. Here the choice is not about choosing between higher or lower quality, because all of ESSENTIAL FOODS' meals are premium. Instead, you choose based on your dog's preferences, taste, nutritional profile and everyday life.
A dog with a high activity level has a different energy requirement than a dog with a more moderate everyday life, and that is worth bearing in mind when you put together the meals. If you would like to find the taste and nutritional profile that best suits your dog, a trial meal can be a good way to let the dog show you the way itself. If your dog has a sensitive stomach, you can find relevant meals gathered with digestion in mind in the collection for sensitive stomach, where you can calmly find what suits best.
How to give the puppy the best start on the way to adult life
The path to a well-functioning adult dog begins long before the dog is fully grown, and the foundation is laid during puppyhood. A puppy that grows with the right nutrition and at a calm pace gets the best conditions for a healthy adult life. It is therefore worth taking the puppy phase seriously - both with training, socialisation and with the right puppy meals.
ESSENTIAL FOODS' BEGINNING range is created for the finest start with luxurious, grain-free puppy meals made from fresh produce, human-grade ingredients and carefully selected local and regional delicacies - completely without grain and unnecessary fillers. If you want to dive deeper into everything from feeding to development and the many questions that come with a new puppy, you will find advice directly from ESSENTIAL FOODS in the well-thought-out Puppy universe, where you can learn more about every step on the way to adult life.
When your adult dog one day steps into its golden years
Adult life lasts a long time, but at some point the dog moves on to its senior years, and this too is noticed earliest in small breeds and latest in large ones. A senior dog's everyday life changes gradually - the pace may become a touch calmer, and the need for rest a little greater - and this is also reflected in what suits best on the plate. It is worth keeping an eye on, so you can adjust the meals when the time comes.
For that phase, the Senior meals are composed with the senior dog's well-being in mind, so the golden years can be lived with appetite and vitality. But that lies some way off in the future for the newly grown adult dog. Right now it is about enjoying that your dog has reached adult life - with a body that has finished growing and many good years ahead, where the right meals help keep it in fine shape. Should you at any point become unsure about anything health-related with your dog, a vet is always the right one to contact, while ESSENTIAL FOODS' nutrition advisers are ready when it comes to feeding and nutrition.