When Do Dogs Stop Growing? A Guide to Canine Growth Stages

All puppies eventually grow up, but the rate at which they do so can vary greatly. In general, dogs will have stopped growing by the time they are a year old. That said, smaller dogs may stop growing as early as 6–8 months, while larger and giant dogs can continue to grow until they are 15–24 months. A number of factors, including genetics, nutrition, and health, can impact how quickly a dog grows.

In this article, we will take a closer look at the growth stages of dogs, drawing on studies from veterinary science and animal biology to help explain the progression from puppyhood to physical maturity.

We will cover everything from breed-based differences in growth to the impact of nutrition and health on a dog’s growth rate to the role of genetics in determining when a dog will reach their full size. By the end, you will have a thorough understanding of what to expect as your puppy grows into a full-sized dog.

Slow and Steady: Canine Growth and Development Timelines

From the moment they are born, puppies are on a path to adulthood, but the milestones they reach along the way are largely determined by their breed size. According to PetMD, small breeds like Chihuahuas and Dachshunds, which will weigh less than 25 pounds as adults, will have finished growing between 10 and 12 months of age.

Medium-sized breeds, which will weigh between 25 and 50 pounds as adults, will have finished growing between 12 and 15 months. Meanwhile, large breeds, which will weigh more than 50 pounds as adults, will have finished growing between 16 and 18 months.

Larger dogs take longer to grow because their bigger bones need more time to be strengthened by calcium, says Dr. Sara Redding Ochoa from White House Veterinary Hospital. In fact, giant breeds like Mastiffs and Great Danes may not reach their full size until they are between 2 and 3 years old.

While genetics determine the rate of growth, they also determine the potential size of a breed, making genetics a key factor in this timeline. This is especially true for purebred dogs, where breeders can often predict growth rates based on the patterns they see in a dog’s family, according to the American Kennel Club.

On the other hand, mixed-breed dogs are much harder to predict, because their genetic makeup is so varied, which shows just how unique each dog’s growth process is.

Fueling Growth: The Nutritional Basics of Puppies

A puppy’s growth and development are dependent on proper nutrition. According to the Clinical Nutrition Service at Cummings School, this means that a diet that is complete and balanced is especially important for large and giant breed puppies like Great Danes, who go through growth periods that can make them more susceptible to the negative effects of malnutrition.

Puppies can be at risk for obesity and orthopedic diseases that can limit their quality of life if they are overfed or underfed in terms of calories.

The negative effects of malnutrition can range from mild, like poor growth and skin problems, to severe, like skeletal malformations and heart disease. To make sure that your puppy grows properly, it’s important to carefully manage their diet. It’s recommended that you keep your puppy at a body condition score of 4 to 5 out of 9 to avoid developmental orthopedic diseases, especially in large breeds.

You can help make sure that your puppy is growing properly by using tools like the WALTHAM™ Puppy Growth Charts, which can help you keep track of your puppy’s growth by providing a standard for comparison.

By plotting your puppy’s weight on growth curves, you can make sure that they are growing at a healthy rate. If you notice that your puppy’s growth deviates from the standard curves, it’s important to talk to your vet about potential changes to their diet.

Proper nutrition and monitoring of your puppy’s growth can help ensure that they get off to a healthy start. This start can be impacted by other factors like spaying and neutering, which will be discussed later.

Neutering/Spaying's Impact on Canine Growth

Neutering or spaying a dog has a big impact on growth, especially when it comes to the timing of growth plate closure. An article in the IAABC Foundation Journal notes that gonadectomies, which are the removal of the sex organs, can delay the closure of growth plates, which can result in longer legs and an increased risk of orthopedic issues like hip dysplasia or cruciate ligament disease.

Especially if the surgery is done before the dog is six months old.

Veterinarians are still debating the health implications and best time to neuter or spay. Dr. David Lane says that while the traditional time for these surgeries has changed, there is no one-size-fits-all answer in an article in the IAABC Foundation Journal. Instead, he says that decisions about when to neuter or spay should be based on the dog’s breed, history of disease, and the purpose for which the dog is being used.

A study in PMC agrees that the relationship between neutering/spaying and long-term health is complicated and says that the best approach is to take an individualized look at the risks and benefits of these surgeries, including the risk of obesity, urinary incontinence, and different types of cancer.

While dog owners should be aware of the impact of gonadectomy on their dog’s growth, veterinarians are well-positioned to offer advice that will help dog owners make choices that will support their dog’s health in the long run.

Promoting Healthy Development: Exercise and Your Developing Puppy

In addition to the mental and emotional benefits, puppies require exercise for musculoskeletal development, which is a critical part of their overall healthy development. A study published in PMC found that different breeds have different activity levels, with larger breeds needing more exercise.

That said, it’s important to adjust the type and amount of exercise to the puppy’s age and stage of development. For example, the “Five Minute Rule” suggests five minutes of exercise per month of age, up to twice a day, until the growth plates close, as outlined by Canine Health & Rehabilitation.

Puppies are at risk of developmental issues if they are over-exercised, especially when it comes to their growth plates, which are the areas of cartilage tissue at the ends of long bones. As noted in the book My Lame Dog, excessive stress on the growth plates before they close can lead to orthopedic problems. However, normal play and exercise are unlikely to damage the growth plates and can help build strength and coordination.

Let puppies regulate their exercise and rest by letting them play as they choose, as their wild ancestors would, and by avoiding high-impact activities until they are fully grown. This way of exercising not only helps ensure proper development but also helps set puppies up for a successful move into the next stage of development, when their genetics will have an even greater impact on their physical development.

Genetics of Canine Growth

The genetic determinants of canine growth are incredibly complex. A study by the National Institutes of Health found that the IGF-1 gene plays a major role in determining small body size in dogs of different breeds. These genetic differences have been used by breeders to control the size and growth rates of dogs, helping to create the wide variety of body shapes and sizes we see in dogs today.

The genetics of mixed-breed dogs is even more complicated. Their diverse genetic backgrounds can introduce multiple genes that control body size, making it even harder to predict how a dog will grow. A study published in PMC has expanded on this research by showing that a cluster of genetic markers near several candidate genes, including GHR and SMAD2, explains a large portion of the size differences in non-giant dog breeds.

While the genetics of our dogs’ growth is complex, it’s also incredibly interesting and useful. This information can help us understand the growth patterns of specific breeds and help us anticipate potential growth-related problems, enabling us to better care for and support our dogs as they grow.

Conclusion: Let the Dog Growth Begin

After asking the important question of when do dogs stop growing, we’ve learned that a dog’s breed, diet, health, and genetics all factor into the equation. Small dogs typically stop growing between 6–8 months, while larger dogs can keep growing until they are 15–24 months old. The decision to spay or neuter a dog can also impact the hormones that impact the growth plates and, therefore, a dog’s growth.

Of course, a dog’s diet is also a key factor in a dog’s growth and development. A well-balanced diet can help prevent growth disorders and ensure a dog grows as they should. When paired with exercise that’s appropriate for a dog’s breed and age, these things can help ensure a dog grows up healthy and strong.

Of course, responsible dog ownership is also important and that means making sure a dog is eating a healthy diet, getting enough exercise, and seeing the vet regularly.

As we move through the stages of dog growth, we can enjoy watching our dogs grow from a rambunctious puppy into a well-behaved adult, which is a confirmation of the special relationship between people and dogs. This progression, which is full of growth, lessons, and love, also shows the great responsibility of raising a puppy into a healthy adult dog.