The Right Age For Dogs To Have Puppies

Dogs are considered puppies until they reach adulthood, which is generally between 12 and 18 months, depending on the breed. Smaller breeds tend to mature faster and may be considered adults by 12 months, while larger breeds can take up to 24 months to reach adulthood. During puppyhood, they go through various developmental stages, including physical and emotional maturation, and their energy levels start to plateau.

Smaller breeds mature faster

Smaller dog breeds mature faster than larger breeds due to their genetics and metabolism. Smaller breeds have a faster metabolic rate and, therefore, reach maturity quicker. On the other hand, larger breeds have slower metabolic rates, take longer to mature, and tend to live longer. This is because their bodies need more time to grow and develop.

Dogs under 30 pounds, such as toy and small breeds, can reach full maturity at any time between 9 and 12 months of age. In contrast, large and giant breeds weighing more than 80 pounds can take up to two years to reach maturity. Medium-sized dogs, which weigh between 30 and 80 pounds, typically transition from puppyhood to adulthood within a year, but some may take up to 16 months.

The generally accepted rule for dog maturity is that a dog under one year old is a puppy, and anything older is an adult dog. However, recent research has shown that this is not always true, and the time it takes for a dog to mature depends on its breed and size.

Smaller dog breeds tend to have shorter gestation periods than larger breeds. The gestation period for dogs typically ranges from 56 to 72 days, with an average of 63 days. Big dogs generally have slightly longer pregnancies than small dogs. For example, a Chihuahua may have a gestation period of just 58 days, while larger breeds such as English Bulldogs may require a C-section to give birth safely.

Emotional maturity

The ideal window for a puppy to stay with its mother and litter is between eight and twelve weeks. During the first four weeks, puppies are entirely dependent on their mothers for nourishment and protection. The mother's first milk, known as colostrum, is rich in antibodies and nutrients that protect the puppies from illnesses while their immune systems are still developing. This milk provides all the nutrition the puppies need during the initial weeks after birth.

From six to eight weeks of age, puppies learn vital canine manners and behaviours from their mothers and littermates. They engage in rough play, practising hunting and communication behaviours that are essential for their future. One of the most critical skills they learn during this period is bite inhibition, which teaches them to control the strength of their bite. Puppies that miss out on this early learning opportunity often struggle with biting, a common problem that can lead to behavioural issues and even relinquishment to shelters later in life.

Additionally, puppies need this time to develop their social and emotional skills. They learn to communicate with their siblings and mother, practising a variety of vocalisations and body language cues. This early critical socialisation period, from approximately five to fourteen weeks of age, shapes how they interact with other dogs and people for the rest of their lives. Puppies that are separated from their litter too early often struggle to interpret other dogs' signals correctly and may exhibit inappropriate behaviours.

Therefore, it is essential to allow puppies to reach this level of emotional maturity before separating them from their mothers and littermates. This typically occurs around eight weeks of age, when they are eating solid food and have benefited from socialisation within their litter. Some breeders may even keep the puppies until ten or twelve weeks of age, especially with toy breeds, to ensure they have a strong foundation for their future development and well-being.

Physical maturity

Puppies are considered adult dogs when they reach one year old, but they continue to grow in height and size while their bones are still developing, which takes anywhere from 6 to 24 months. Their skeletal growth determines how tall they will become as adults. The growth plates—two distinct places where new tissue is formed—are flexible and soft during puppyhood. As the puppy grows, the new tissue hardens into bone. When the growth plates stop producing new tissue and become completely calcified, they are said to have 'closed', which means the bone has reached its final size.

Small and medium puppy breeds grow up pretty quickly. On average, small breeds typically stop growing by the time they reach 6 to 8 months of age. Medium breeds might take a bit longer, reaching their adult size at around 12 months of age.

A larger dog takes a bit more time than a smaller one to reach full adult size because those bigger bones need more time to grow. Giant breed puppies grow until they are 12 to 18 months old. Large to giant breed pups usually weigh 70 or more pounds as adults. In some cases, very large pups like mastiffs may even reach their fully grown size at 24 months of age.

Sexual maturity in puppies typically begins to occur between 6 and 9 months of age, although certain giant breeds may take longer to mature. Male dogs are sexually active year-round and can sire puppies when they're as young as 5 months, but they are most fertile after 12 to 15 months of age, once they are fully physically mature. Female dogs' first heat usually starts between 6 and 15 months of age, then once they're mature, will occur approximately every seven months.

Puppy food vs adult dog food

The main difference between puppy food and adult dog food is that puppy food is much higher in calories, specifically in the form of proteins and fats. Puppies need a lot of energy to fuel their growth and development, and they burn a lot of calories through exercise and play. They also need extra calories to help regulate their body temperature, as they are not yet as efficient at this as adult dogs.

Puppy food contains a higher percentage of calories from protein than adult dog food, with vets recommending that puppies get 22.5% of their calories from protein, and adult dogs 18%. Puppy food typically contains between 30-40% protein, while adult dog food contains 20-25%.

Puppy food also contains a lot more fat, with some formulas containing as much as 20% fat, while adult dog food contains less than 10%.

Puppies also need specific amino acids to create muscle and tissue, which are principally found in meat proteins. These include phenylalanine-tyrosine, which puppies need to ingest about twice as much of as adult dogs. DHA, a fatty acid found in mother's milk, is also important for cognitive development and eyesight in puppies.

Minerals such as calcium and phosphorus are essential for puppy skeletal development. Puppies need at least 1% calcium and 0.8% phosphorus in their diet, while adult dogs only need 0.6% and 0.5% respectively.

The calorie density of puppy food is generally higher than that of adult dog food, and it is important to monitor a puppy's body condition and growth rate to ensure they are not growing too quickly, which can cause obesity and skeletal deformities.

The best time to switch from puppy food to adult dog food is when a puppy reaches about 80% of its predicted full size. This varies depending on the breed, but generally, smaller dogs reach maturity faster and are usually fully grown by one year, while larger dogs may take 2 to 3 years to reach their full size.

It is recommended that you gradually transition your dog from puppy to adult food over a period of about a month, starting with a mix of 80% puppy food and 20% adult food, and slowly adjusting the ratio until you are feeding them only adult dog food.

While it won't cause any immediate harm, it is not recommended that puppies eat adult dog food, as it does not contain the specific nutrients they need to grow and develop, and it could lead to health issues such as obesity, high cholesterol, and heart problems. Similarly, adult dogs should not eat puppy food, as it is too rich and calorie-dense, and can cause them to gain weight.

On a separate note, while searching for information about the differences between puppy food and adult dog food, I came across some information about dog pregnancy that might be of interest. The normal gestation period for dogs is approximately 63 days from conception, and pregnancy in dogs is relatively short compared to humans, at about 9 weeks total.

Puppy growth plates

Until fusing completes at sexual maturity, these soft areas are much more prone to injury from hard impacts, repetitive impacts, and even too much exercise. A fracture during this time can cause problems for proper healing, prevent the growth plate from fully forming, and create uneven pressure on the other legs, resulting in secondary physical health challenges over a dog's lifetime.

Growth plates close at a predictable age, based on the size of the dog. Toy and miniature breeds generally have closure of growth plates at 6-8 months of age, while some growth plates of large or giant breeds of dogs may remain open until 14-18 months of age. Small and medium puppy breeds grow up pretty quickly, with small breeds typically stopping growth by the time they reach 6 to 8 months of age. Medium breed puppies might take a bit longer to grow, reaching their adult size at around 12 months of age. A larger dog takes a bit more time than a smaller one to reach full adult size because those bigger bones need more time to grow. "Giant breed puppies grow until they are 12 to 18 months old," says Dr. Klein. Large to giant breed pups usually weigh 70 or more pounds as adults. In some cases, very large pups like mastiffs may even reach their fully grown size at 24 months of age.

To avoid growth plate injuries, puppies need the right amount and type of exercise for their age. Examples of good exercise include playing with other dogs/puppies of similar energy levels and short walks that lengthen over time. As your puppy grows, you can then progressively introduce activities like stairs, jumping, and swimming.

Frequently asked questions