Sexual Maturity in Puppies: What to Expect

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Maturity occurs the same way with all puppies. One moment you have a cute little puppy in your arms and the next they’re acting out against you—kind of like a mini teenager!  By this stage, your puppy is putting their independence to the test, often displaying behaviors that you wouldn’t expect from such an adorable […]

Maturity occurs the same way with all puppies. One moment you have a cute little puppy in your arms and the next they’re acting out against you—kind of like a mini teenager!  By this stage, your puppy is putting their independence to the test, often displaying behaviors that you wouldn’t expect from such an adorable little creature. 

Sexual maturity is usually the cause of many behavioral problems during a puppy’s “teenage” phase (also known as their adolescent period). Along with testing your patience, your puppy will display natural impulses that signify their gradual journey toward adulthood. Whether we like it or not, we need to address our puppy’s maturation process to be good dog owners. 

Here is a quick guide on what you should expect about your puppy’s sexual maturity and how to prevent accidental litter.

At what age are puppies considered sexually mature?

Sexually maturity in puppies varies on their breed and size. For larger breeds, sexual maturity may not occur until after the 9-month period while smaller breeds usually begin at around 6 months. Most veterinarians will observe your puppy’s growth plates—the soft areas around their bones—to see if they’re almost ready to close. 

In most puppies, growth plates usually begin closing at around the 9-month mark, though some breeds may need a little longer. It’s important to know what age your puppy is sexually maturing to avoid neutering or spaying them too early. 

According to Urbana Veterinary Clinic, neutering and spaying your puppy at an early stage can lead to a multitude of health problems in adulthood. Consult with your veterinarian if you aren’t sure what age your puppy enters sexual maturity. 

What are signs that a puppy is sexually mature?

When children hit puberty, there are plenty of telltale signs that let parents know it’s happening. Luckily for puppies, they don’t suffer through acne, body odor, and hair sprouting in weird places, but they do go through a similar transformation. 

And like humans, these hormonal and behavioral changes occur differently in males and females. Here’s a quick rundown of the signs and symptoms of sexual maturity in puppies:


Most female puppies go through their first heat at around the 6 month period, though it can occur much later depending on the breed and size. Heat, also called the estrous cycle, is a period in a female dog’s life where she can get pregnant. Key signs that your puppy may be “in heat” include:

  • Swelling in her private area
  • Frequent urination
  • Constant licking
  • Red vaginal discharge (a bit like human menstruation)
  • Constant roaming around, especially outside
  • Aggression towards other dogs

Remember: even if your puppy is only 6 months old when she goes into heat, she is able to get pregnant. Keep a close eye on her whenever you’re outside. Do not allow any male dogs near her if you’re not planning to have a litter of puppies. 


Male dogs do not go through the estrous cycle (“heat”) as females do. Because of this, they can sire puppies at any time of the year. 

Male puppies start their sexual maturity as early as 5 months old. However, their fertility is at its peak after they’re 12 months old. At this point, their testosterone levels are higher than usual, leading to aggressive behavior. Other signs of sexual maturity in male dogs are:

  • Roaming around, especially if a female in heat is nearby
  • Territorial marking
  • Humping
  • Anxiety
  • Overprotective behavior

An aggressive or anxious dog is likely to get into fights with other male dogs. Territorial marking is another sign of sexual maturity that can be annoying or frustrating for many owners. 

It’s important to keep your dog on a leash and consider getting your puppy neutered to prevent any undesirable traits. You can also play fun physical and mental games with your puppy and reinforce their training. 

It can be challenging to deal with a puppy during this important stage in their development. You may find yourself wanting to give up, but always remember that this is temporary. Be patient and have faith in your furry friend. 

What are spaying and neutering?

One of the most important decisions you’ll ever make in your puppy’s life is getting them spayed or neutered. Once your puppy reaches sexual maturity, they may display behaviors you won’t like territorial marking, aggression, and roaming. If you aren’t planning on breeding your puppy, we highly recommend spaying or neutering your puppy. 

Spaying and neutering your furry friend has several benefits—and not just stopping undesirable behaviors. According to Pawsome Advice, spaying and neutering give your puppy a longer lifespan so you’ll have many years to spend loving them! 

Choosing the best time to spay or neuter your puppy depends on its age. Many vets recommend waiting until your female pup has had its first heat cycle before spaying her. This will prevent her from developing canine breast cancer as an adult. For males, your vet may recommend waiting until your puppy reaches a certain age. 

When in doubt, consult your vet for advice on spaying and neutering your puppy. They will likely base their suggestions on your furry friend’s age, size, and breed. You can also check out our guide, Spaying and Neutering Dogs: What You Should Know for the best information about spaying and neutering your puppy.

Also, don’t feel sad or guilty about having your puppy undergo the procedure. At the end of the day, you’re doing what’s best for your little buddy. Spaying and neutering help eliminate several health issues that dogs face as adults. By spaying or neutering your puppy, you’re letting them know that you care about their health!

We all know how awkward and scary puberty can be for adolescents. While their hormonal and behavioral transformations are different than ours, your puppy is going through a confusing time in its life. Be patient and cut them some slack.

Your little fur-baby is acting purely on animalistic instincts so don’t take their sudden aggression personally. Continue reinforcing your puppy’s training and talk to your vet about spaying or neutering. By the time their awkward phase is over, your doggy will be back to their normal goofy selves! 

Taking your puppy to the vet is an important first step to good health! Check out our blog, Your Puppy’s First Vet Visit for our helpful tips!