Sexual Maturity in Puppies: What to Expect

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Maturity is a process that all puppies must go through before adulthood. You can call this process “puppy puberty” because your little fur-baby will undergo many changes—some of which may come as a surprise to you!  Along with growth spurts, your cute puppy may showcase some peculiar behaviors. They may start acting out against you, […]

Maturity is a process that all puppies must go through before adulthood. You can call this process “puppy puberty” because your little fur-baby will undergo many changes—some of which may come as a surprise to you! 

Along with growth spurts, your cute puppy may showcase some peculiar behaviors. They may start acting out against you, testing your limits, and ignoring your commands…like a mini rebellious teenager! If that sounds like your puppy now, don’t take it to heart.

During their sexual maturity phase (also known as their adolescent period), your puppy is experiencing a multitude of behavioral and hormonal changes that are confusing. Their natural instincts will tell them to lash out and display other behaviors that you probably won’t like. 

Unfortunately, during the sexual maturity phase, puppies may adopt certain undesirable traits that will stick with them as adults. A clueless puppy parent may not know how to deal with their puppy’s new rebellious streak.

That’s why it’s important to learn about your puppy’s sexual maturity phase and the process behind it so you can be there for them!

At what age are puppies considered sexually mature?

Sexual maturity in puppies depends on their breed and size. Like children, some breeds start maturing earlier than others. Most larger breeds are late bloomers, rarely starting sexual maturity until after they’re 9 months old. 

Smaller breeds get a head start, usually at 6 months of age (if not earlier). When checking for sexual maturity, most veterinarians will check your puppy for their growth plates. Growth plates are the soft areas around your puppy’s bones. If these plates are almost ready to close, then your puppy is maturing. 

Most puppies will have their growth plates start closing at around 9 months of age. Some breeds will take longer for these plates to close. Your puppy’s growth plates need to be ready before you spay or neuter them. 

Neutering or spaying your puppy too early can lead to a list of health issues during adulthood—something you definitely don’t want to deal with.

When in doubt, always consult your vet. They will know whether your fur-baby’s growth plates have started closing and at what age your puppy should be neutered or spayed.

What are signs that a puppy is sexually mature?

Ah, puberty…we’ve all been there! The acne, body odor, the sudden growth spurt—it’s an awkward time in an adolescent’s life. While puppies won’t exactly get acne from puberty, they do suffer through hormonal and behavioral changes that drive them (and us) crazy. 

Here’s a quick list of things you can expect from your puppy’s adolescent period: 


All female puppies undergo the estrous cycle, also known as “heat” during their sexual maturity phase. It typically starts at the 6-month mark, though some breeds may experience it much later. 

When a female dog is “in heat”, it is the only period in her life where she is able to become pregnant if you aren’t careful. A few signs that your little puppy is in heat include:

  • Swelling in her vaginal area
  • Licking around her vulva
  • Frequent urination, especially territorial marking
  • Bloody discharge (resembles a human period)
  • Roaming
  • Aggressive behavior

Take note: puppies can still become pregnant even if they go into heat at 6 months. If you don’t want your pup to become pregnant, pay attention to her when you take her outside. 

Do not let any male dogs near her. She will not fight off their advances and you may end up with unwanted litter if you aren’t careful.


Male dogs do not have an estrous cycle (“heat”) as females do. They can sire puppies all year long and will take any opportunity to do so if a female in heat is nearby. 

Male puppies may start their adolescent period at 5 months of age. However, their fertility peaks after they turn 12 months old due to high testosterone levels. This also causes them to display aggressive behavior, which can turn into a problem.

Other signs of sexual maturity in male dogs are:

  • Roaming
  • Territorial marking
  • Humping
  • Whining or crying
  • Anxiety
  • Overprotectiveness

An aggressive or anxious male dog tends to fight with other male dogs. If you have two male dogs near a female in heat, there’s a huge chance they will start attacking each other, even if they’ve grown up together.

Territorial marking is another common sign of sexual maturity. While your little puppy may just be marking their scent, you may not find it amusing.

It’s important to keep your male dog on a leash whenever you venture outside. Maintaining your puppy close can prevent dog fights and roaming. You should also consider getting your male dog neutered to prevent undesirable behavior from occurring. 

Try playing physical and mental games so that your puppy is always entertained. Continue training your puppy as well. And of course, have patience. Dealing with puppies at this stage is frustrating—we know.

Remember that their adolescent period is temporary. Your puppy won’t stay like this forever. Have faith in your furry friend just like they have faith in you!

What are spaying and neutering?

Getting your puppy spayed or neutered is an important decision that you’ll make in your puppy’s life. During their adolescent period, your little buddy may display bad behavior that often frustrates puppy parents like territorial marking, aggression, roaming. We recommend spaying or neutering your puppy as soon as they are able to do so.

Besides preventing bad behavior, spaying or neutering your puppy has countless key health benefits. According to Dayton Daily News, unneutered male dogs can develop testicular cancer, prostate infections, and prostate enlargement over time. Similarly, female dogs that aren’t spayed may develop life-threatening health conditions such as pyometra (a severe uterine infection) and mammary tumors.

Spaying or neutering your puppy is the best way to ensure they have a long and happy life with you! However, choosing the best time to spay and neuter your puppy can be tricky. It depends on age and breed.

While there are disagreements about the best time to neuter a puppy, most vets agree that waiting until a female pup has had her first heat cycle is the best option. Waiting until her first cycle prevents your puppy from getting canine breast cancer in adulthood. In males, your vet may advise you to wait until they reach a certain age.

Always talk to your vet for accurate, up-to-date information about spaying and neutering your puppy. Your vet will assess your puppy and make suggestions based on certain key factors, such as age, size, and breed. 

Some puppy parents feel guilty about spaying or neutering their puppy. They may feel that they’re taking something away from their furry friend or causing them pain. At Petland, we’re here to say: don’t feel sad or guilty about it!

Spaying or neutering your fur-baby prevents countless health conditions that they can face as adults. By spaying or neutering your little buddy, you help them live a happy, healthy life with you!

Puberty is such a scary time for puppies. Their hormonal and behavioral changes may be different than ours but it’s so confusing for your puppy too! Whatever your puppy does or doesn’t do, be patient and don’t take their actions personally.

Your puppy can’t help their instincts so if they take their aggression out on you, know that they didn’t mean it. Reinforce your puppy’s training and keep in touch with your vet about your options. Once their adolescent period is over, your pooch will go back to their regular old selves!

Do you have a high-energy puppy? Check out our blog, Tips to Tire Your High-Energy Puppy Out to learn how to handle your energetic little friend!