Puppy puberty and heat cycles explained

Puppies experience physical and behavioral changes when they reach puberty, usually between seven and nine months. Reproductive hormone levels change as puppies mature, leading to physical and behavioral changes. Puberty can be a difficult time for puppies and pet parents, so it’s important to know what’s normal and when to reach out to a veterinarian for help. Read on to learn more about:

• Dog life stages
• Signs of puberty in puppies
• A female dog’s heat cycle
• How pet parents can help their puppies through puberty

The age at which a puppy reaches puberty varies between size and breed, with larger breeds typically reaching maturity at a later age than small breeds. When puppies become sexually mature, they experience several physical and behavioral changes. Female puppies go through heat cycles involving bloody vaginal discharge and changes in behavior. These signs indicate they are sexually mature and able to get pregnant. Male puppies also experience behavioral changes and may begin to mark territory and show more interest in humping or mounting behaviors. It’s good to know what to expect, what’s normal, and when to reach out to a vet for help.

Adolescence is defined as the stage when a human goes through puberty and develops from a child into an adult. While dogs go through puberty as they become sexually mature, they don’t have a similarly defined life stage.

The life stages of a dog identified by the American Veterinary Medical Association (AVMA) include:

• Puppy
• Young adult
• Mature adult
• Senior
• End of life

People observing the physical and behavioral changes their pubescent puppies go through may wonder if dogs experience something similar to adolescence in humans. A 2020 study found that dogs going through puberty might experience heightened conflict with their human caregivers, often becoming less responsive to commands and training during this period. This suggests that puppies may go through something like adolescence in humans, but more research is needed to fully understand this.

When do puppies go through puberty?

The exact age at which a dog transitions from one life stage to the next varies between breeds and individuals, but the average age a puppy reaches puberty is seven to nine months of age, with a range of four to twenty-four months. Giant breeds may not reach maturity until they are much older compared to smaller breeds. As a puppy becomes sexually mature, the levels of reproductive hormones change. These changes in estrogen, progesterone, and testosterone levels can lead to changes in a dog’s behavior and appearance.

Puppies begin to experience physical and behavioral changes when they go through puberty. Signs of puberty in puppies may include:

• Males marking territory or lifting their leg to urinate
• Males having more interest in humping or mounting behaviors
• Females having their first heat or reproductive cycle
• Increased aggression or destructiveness in an attempt to escape and mate

Puberty for female puppies includes coming into heat for the first time, which is part of their reproductive, or estrous cycle, and is when they are the most fertile. Having heat cycles indicates that a female dog is sexually mature and can become pregnant. Most puppies will experience their first heat between six and 24 months of age. A puppy’s first heat cycle may not be very intense or obvious and can be easily missed by owners. Larger breeds typically have their first heat cycle later than small breeds.

There are four stages of a dog’s heat cycle:

• Proestrus: Estrogen levels peak. Dogs have bloody vaginal discharge and a swollen vulva. The start of the fertile period of the reproductive cycle.
• Estrus: The female dog is receptive to breeding.
• Diestrus: The female is no longer receptive to breeding and has increased progesterone levels, ending the fertile period of the cycle.
• Anestrus: The end of the heat cycle or after having a litter of puppies (whelping). Progesterone and estrogen levels return to normal, and the uterus prepares for the next heat cycle.

Dogs typically go into heat twice a year, roughly six months apart. An irregular cycle may be normal for some dogs, but it may also be a sign of illness. The bloody vaginal discharge lasts an average of a week and a half to two weeks. Spayed dogs will not have a heat cycle and cannot get pregnant, and an unspayed dog can only get pregnant during the estrus stage of the heat cycle.

The signs of a dog in heat

What most owners refer to as “being in heat” refers to the proestrus and estrus stages of the estrous cycle when female dogs have bloody vaginal discharge. Behavioral and physical signs of heat in female dogs include:

• Bloody or straw-colored vaginal discharge
• Swollen vulva
• Frequent urination
• Excessive licking of genitalia
• Becoming more receptive to male dogs
• Standing to be mounted
• Agitated, nervous, or aggressive behavior

Behavioral changes can be mild to severe and can vary widely, depending on the individual dog. Not all dogs in heat will display the same behaviors or every behavior on the list above.

The age at which sexual maturity occurs in dogs varies. Larger breeds generally reach sexual maturity later than smaller breeds. Most female dogs will reach sexual maturity between the ages of six and twenty-four months, but some can start their first heat cycle as early as four months old. Most males reach full sexual maturity between the ages of 12 and 15 months but can breed as young as six months of age.

The easiest way to get through a puppy’s puberty phase is to avoid it entirely, as dogs do not go through puberty at all if they are spayed or neutered before it starts. If you and your veterinarian have decided to wait until after the onset of puberty to spay or neuter your dog, there are a few ways you can help your puppy through this new time in their life. Always be patient and gentle with your puppy during this period. Behavioral issues associated with puberty are often temporary and are best worked through with patience.

Some things you can do to help your puppy get through puberty are:

• Start training your puppy before the onset of puberty
• Provide plenty of exercise and mental stimulation
• Keep females in heat away from male dogs and supervise them, even in fenced yards
• Do not take female dogs in heat to dog parks or other public places with a lot of other dogs

Female dogs in heat are very interested in being bred, and intact male dogs are highly motivated to find and breed with them. A chain link fence will not stop them from mating, and dogs can be highly motivated to escape from a fenced area or home to mate.

Talk to a vet if you need help with behavioral issues, such as your dog escaping the yard, and to discuss the best time to spay or neuter your puppy. It’s usually recommended to spay or neuter dogs that will not be bred to prevent unwanted pregnancies and various health issues.

When to talk to a vet about your puppy’s hormonal changes

“Talk to a veterinarian any time you are worried about your puppy,” states Jo Myers, a veterinarian on Vetster. “It can be difficult to tell if new behaviors are normal or might indicate a medical problem.” Talk to a veterinarian right away if:

• Signs of heat last longer than 21 days
• A spayed female shows signs of heat
• A puppy is not showing signs of growth or sexual maturity

If you have questions about canine puberty, heat cycles, signs of illness, or behavioral changes, veterinary professionals are available 24/7 on Vetster for online virtual care appointments to help give veterinary advice and answer questions.

Do dogs go through adolescence?

The period when a dog’s hormone levels change as they reach sexual maturity is referred to as puberty. It’s sometimes compared to the adolescent phase in human growth and development. There’s a study suggesting that pubescent dogs go through a phase of conflict targeted at their caregivers, similar to many human teenagers.

What are the signs of heat in dogs?

Heat is part of the reproductive cycle in female dogs, indicating they are sexually mature and able to get pregnant. Signs of dogs in heat include bloody discharge from the vagina, a swollen vulva, and becoming more receptive to male dogs. Some dogs may show behavioral changes, such as more frequent humping or appetite changes, while others may show few to no changes.

What are the common behaviors of a dog during puberty?

Male and female dogs experiencing puberty go through physical and behavioral changes. Female dogs go into heat for the first time, but it can be easy to miss if it’s not very intense. Both males and females show interest in mating. Other common behaviors may include increased interest in humping, marking territory, and roaming.