When you first see a newborn puppy, it’s really hard to believe that in a matter of months, this tiny lump of puppy will soon grow almost as large as its parents. When will your puppy stop growing? Here’s what to expect.

By Doug Jimerson
August 24, 2020
Each product we feature has been independently selected and reviewed by our editorial team. If you make a purchase using the links included, we may earn commission.
Advertisement
anitapeeples / Getty

Remember the story of Clifford, the Big Red Dog? According to the beloved children's tale, the love of Emily Elizabeth made Clifford grow and grow and grow—topping out at nearly 25 feet tall! 

If you’ve watched how quickly a puppy grows, you may have wondered briefly if yours would ever stop growing—or end up super-size like Clifford. While no one can tell you for sure how big your puppy will be when she's done growing or when that growth will stop, there are some factors that can give some hints.

Puppy Growth Factors

Puppies grow fast. In fact, most puppies will double their birth weight in the first week of life. When will your puppy stop growing? The answer depends on a few factors:

Large Breeds vs. Small Breeds

With dogs, the smaller the breed the faster it reaches maturity. Smaller breeds can reach their mature size and stop growing in just 8 to 10 months. Chihuahuas, toy poodles, Yorkshire terriers, and Maltese are just a few examples of breeds that reach adult size in about a year. On the other hand, giant breeds such as Great Pyrenees, Great Dane, Saint Bernard, Irish wolfhound, and English mastiff may not fully mature for up to two years.  

Male vs. Female

Male and female puppies of the same breed will grow at similar rates, and they’ll stop growing around the same time. But females will generally end up being smaller than males. Even within the same litter of purebred dogs, individual pups of both sexes will vary somewhat in size. The size discrepancies may be even greater in mixed-breed puppies, since they carry the DNA of different breeds. 

Supporting Healthy Puppy Development

While breed and gender are major influences on how long your puppy will be growing and how big he will be, there are some other factors that can ensure proper growth and development.

Provide a Healthy Diet

Because puppies grow so fast, it’s important that they remain on a high-protein diet especially designed for them until they are at least 6 months old. Larger breeds or any dog that is expected to top out at 70 pounds or more should be fed a puppy food designed for large breeds. These foods will have a balanced mix of calcium and phosphorus to help prevent skeletal problems later in the dog’s life. Always check with your veterinarian about the type of dog food you should offer and how often you should feed your puppy as it grows. 

Activities to Avoid

All puppies love to play, but because they are actively growing, activities that could impact ideal bone and joint development should be avoided until your pet reaches adult size. These include running on hard surfaces such as concrete or asphalt, jumping or twisting to catch a Frisbee or ball, walking on slippery floors or stairs such as tile or hardwood (use throw rugs to provide stability), or any type of repetitive activity such as exercising your pup on a treadmill. 

Stages of Emotional Development

And it's not just your puppy's physical growth that you should be concerned about. Making sure that your dog is growing mentally and emotionally is equally important.

Zazie Todd, PhD and author of Wag: The Science of Making Your Dog Happy says that puppies go through several stages of emotional development as they grow. “From 3 to 14 weeks, they are in a sensitive period for socialization,'' she says. Following that, they enter the juvenile period. 

Puppies gain a wide range of experiences in all stages, and Todd stresses that you want to give your pup positive experiences as they grow. “Negative experiences can cause fear,” she says. Patience and positiveness are important, especially as your puppy ages. “Teenage dogs are like teenage humans: They might not always do what you want them to do,” Todd says, but training them with positive reinforcement builds them into loving, confident pets.