When to switch a puppy to adult food

Two sets of ages

Ask two good sources and you get two answers. The American Kennel Club suggests switching at about 7 to 9 months for dogs expected to weigh under 20 lb as adults, and at about 12 to 14 months for larger dogs. The veterinary nutrition team at Tufts University recommends that no puppy, and especially no large-breed puppy, go onto adult food before 12 months. In its posts, small breeds and most large breeds such as Labradors can switch after their first birthday, while giant breeds may keep growing through 18 months.

For small dogs, either answer is reasonable, and the difference is a few months on a food that suits growth. For large and giant breeds, the sources that set the later age are the vet nutritionists, and their reasoning is about bones, as the next section shows. If you aren’t sure which row your puppy belongs in, the puppy weight calculator estimates its adult weight range.

Why switching early matters most for big puppies

Large and giant puppies are sensitive to how much calcium and how many calories they get while their bones are growing. The Merck Veterinary Manual notes that too much calcium is a bigger problem for large and giant breeds from weaning to 1 year. In young, fast-growing large-breed dogs, a diet with more than 3% calcium (on a dry-matter basis) caused more severe osteochondrosis, a joint cartilage disorder. Tufts adds that large-breed puppies are sensitive to too little calcium as well as too much. That is why foods for them must meet a narrower calcium range.

Calories matter too. Tufts warns that too many calories during growth can make puppies overweight, which raises the risk of bone and joint problems. Its advice is to keep growing puppies at a body condition score of 4 to 5 on the 9-point scale. Adult foods aren’t made for growth, and Tufts puts it bluntly: for large-breed puppies, adult diets are more likely to cause growth problems than to prevent them.

Check the label, not the picture on the bag

In the US, the nutrition statement on the bag tells you which life stage a food was made for. AAFCO, the body that writes the model rules, uses four: gestation and lactation, growth, maintenance (adult), and all life stages. Tufts notes that an all-life-stages food meets the needs of both puppies and adults, so a puppy already on one doesn’t need a new food at its first birthday, only a smaller portion.

For big dogs, read one more line. A growth or all-life-stages claim must say whether it includes or excludes “growth of large size dogs (70 lb. or more as an adult),” as state rules based on the AAFCO model require. Tufts suggests treating 50 lb as a safer cutoff than 70, so if your puppy may weigh more than about 50 lb as an adult, choose a food whose statement includes large-size growth.

How to make the switch

Change foods gradually so your dog’s stomach has time to adjust. Tufts suggests at least a week and gives this schedule. It also notes that some pets need four to six weeks.

The amount changes along with the food. In the 2021 AAHA nutrition guidelines, a puppy over 4 months needs about 2 times its resting energy requirement. A neutered adult needs 1.4 to 1.6 times and an intact adult 1.6 to 1.8 times. By our arithmetic, a neutered adult needs about 20 to 30% fewer calories per unit of resting energy than an older puppy. Adult foods also differ in calories per cup, so don’t carry over the old scoop. The dog food calculator works out a new daily amount from your dog’s weight and the label of the new food.

Spaying, neutering and the pudgy puppy

Spaying or neutering doesn’t change when to switch. Tufts says to keep feeding puppy food until 12 to 18 months either way. It does change how much your dog needs later, as the AAHA ranges above show. If your puppy is getting heavy before it is old enough to switch, reduce the amount of puppy food rather than moving to adult food early. Tufts adds that you don’t have to switch at the exact birthday if your dog is at a healthy weight. For a dog that has become pudgy, it suggests an adult food with fewer calories than the current one. The guide to checking whether your dog is overweight shows how to score body condition at home.