Your puppy may have outgrown its favorite bed, collar and even the puppy look, but that doesn’t necessarily mean it’s ready to outgrow its food.
Knowing when to make the switch from puppy food to adult food isn’t as simple as waiting for a dog’s first birthday. Elisabetta Pierangelo, global vice president of research and development at Mars Pet Nutrition, says the timing depends largely on when a puppy has finished growing, and that can vary significantly depending on the dog’s size.
“A puppy’s growth period depends on their future adult size,” Pierangelo told Newsweek.
A puppy reaches adulthood when it stops growing, she explained, which can happen at 10 months for very small dogs or take as long as two years for giant breeds. This means some could be ready to switch to adult food shortly after their first birthday, while others may still have important growing to do.
Pierangelo said puppies should be fed a complete and balanced diet specifically formulated for growing dogs until their growth is complete.
When Should a Puppy Switch to Adult Food?
Rather than using age alone as a guideline, pet parents should pay attention to their puppy’s growth.
Puppies grow rapidly at first, so owners will typically notice changes in their weight, height and body length from month to month. As they approach their adult size, that growth gradually slows and eventually flattens out.
“This is when a puppy is ready to transition to adult dog food,” Pierangelo said.
WALTHAM Petcare Science Institute Puppy Growth Charts can also help pet parents track their puppy’s growth and determine whether it is following a healthy trajectory.
The timeline can be particularly different between breeds and sizes. Dogs can weigh as little as 4.4 pounds or more than 154 pounds as adults, and they don’t all reach that size at the same rate.
Small breeds generally mature sooner, while large and giant breeds can continue growing for much longer.
Why Can’t Puppies Eat Adult Food?
Because puppies are undergoing rapid development, their nutritional requirements differ from those of fully grown dogs.
For example, puppies need up to three and a half times more protein than adult dogs to support muscle growth, tissue repair, immune defense and hormone signaling, Pierangelo said.
Pups require twice as much dietary fat to meet their high energy demands and obtain essential fatty acids that their bodies cannot produce themselves. They also need DHA, or docosahexaenoic acid, an omega-3 fatty acid that supports brain and vision development.
Complete and balanced puppy food is formulated to provide the vitamins and minerals puppies need during development, including appropriate levels of calcium and phosphorus for bone growth and tooth development.
What Happens If You Switch Too Early?
Moving a puppy to adult food before it has finished growing can mean it no longer receives the nutritional balance designed for its developmental stage.
“Switching a puppy to an adult diet too early can severely compromise their development due to nutrient deficiencies or imbalances,” Pierangelo said. “If their intake falls below minimum requirements, their health will rapidly deteriorate.”
She noted that both deficiencies and excesses of certain nutrients can cause problems.
For example, insufficient methionine can lead to a sudden loss of appetite and severe weight loss, while inadequate zinc can impair growth and cause painful lesions on a puppy’s foot pads. Iron deficiency can also result in poor growth, lethargy and weakness.
But more isn’t necessarily better, either. Pierangelo said excessive amounts of certain nutrients can also be dangerous. Too much lysine, for example, can interfere with the absorption of other amino acids, potentially causing muscle tremors and vomiting.
The goal, therefore, isn’t to give a puppy as many nutrients as possible but to provide the right nutrients in the right amounts.
Keep Growth on Track
How quickly a puppy grows can be just as important as how long it stays on puppy food, as growing too fast or too slowly can lead to lifelong health problems, such as hip dysplasia, obesity and other skeletal disorders.
But once a puppy has finished growing and is ready to switch foods, Pierangelo said the change should be gradual, as digestive upset is common in pups. She recommends a change over a period of four to seven days, although some dogs may need longer.
“This should be achieved by adding a small proportion of the new diet to the puppy’s regular diet on the first day,” she said. “The proportion of the new diet should be gradually increased each day, so that it makes up half the puppy’s food on day four and the whole meal by day seven.”
A veterinarian can help determine when a puppy is ready to make the switch, which adult diet is appropriate and how much to feed.