Skip to Content

Do dogs get periods every month?

Many dog owners wonder if female dogs have menstrual cycles like humans do. The short answer is yes, dogs do undergo estrous cycles that are similar to a woman’s menstrual cycle. However, there are some key differences between a dog’s heat cycle and a human period that owners should understand.

Do Dogs Bleed During Their Cycles?

The primary sign that a female dog is in heat is vaginal bleeding. This is why a dog’s estrous cycle is often referred to as her “season” or being “in heat.” The technical term for this vaginal bleeding is proestrus. Female dogs bleed from their vulva when they are in proestrus, which is the first stage of a dog’s heat cycle.

Some key facts about bleeding during a dog’s heat cycle:

  • The bleeding lasts for around 9 days on average but can range from 3 to 21 days.
  • The bleeding is typically light and may not be noticeable on some surfaces.
  • Owners may see blood spots around the house from their dog’s vaginal discharge.
  • Hygiene products like doggy diapers can help keep the mess to a minimum.

So do dogs have periods? Technically no, but the vaginal bleeding that occurs during proestrus serves a similar biological purpose as menstruation does for humans.

What Are The Stages of a Dog’s Estrous Cycle?

A dog’s estrous cycle consists of four distinct stages, which are as follows:


This first stage starts when a female dog begins bleeding from her vulva. It lasts approximately 9 days on average. Eggs in the ovaries start maturing in preparation for ovulation. The bloody discharge starts light and then becomes heavier toward the end of this stage.


During this stage, which lasts about 9 days, the bleeding slows down and then stops completely. Hormone levels in the bloodstream peak. It is during estrus that female dogs are receptive to mating with males. Puppy pregnancy can only occur during this stage.


Diestrus is the longest stage, lasting an average of 90 days. The female dog’s vulva returns to a normal size, and she will no longer be interested in mating. Pregnancy begins developing during this stage.


This final stage is a resting period when the dog’s reproductive system shuts down. It lasts for an average of 120 days. After anestrus ends, the cycle begins again with proestrus.

These four stages comprise the estrous cycle, which repeats about every 6-7 months on average. However, the length of time between heat periods varies dramatically between individual dogs. Some dogs only cycle once a year, while others can cycle three times in a year. The intervals tend to shorten as dogs age.

How Do I Know If My Dog Is in Heat?

Here are the most common signs that a dog is going into heat:

  • Swollen vulva
  • Bloody discharge from the vulva
  • Excessive licking of genital area
  • Increase in urination
  • Behavior changes (restlessness, moodiness)
  • Male dogs strongly attracted to the female

Owners may notice their dog in heat acting irritable or restless. This is from hormonal fluctuations. Be patient with your dog and try to minimize stress during this time.

Provide extra pads or diapers to help contain any discharge and prevent stains. Monitor your dog when she is outside to prevent unwanted mating. The discharge and smell can attract male dogs from far away.

At What Age Do Dogs Go Into Heat?

Most dogs experience their first estrous cycle at 6-12 months old. However, breed plays a major role. In general, smaller breeds mature and start their cycles earlier than larger breeds.

Here are some averages for age at first heat cycle:

  • Small breeds: 6-12 months
  • Medium breeds: 9-15 months
  • Large/giant breeds: 12-24 months

While these are typical ranges, some individual dogs can enter their first cycle as early as 4 months old or as late as 2 years old. Genetics help determine when a puppy will have her first heat.

How Often Are Dog Heat Cycles?

On average, female dogs go into heat twice per year. Their cycles usually come at intervals of 5 to 8 months. But each dog is an individual, and heat cycles can vary dramatically.

Here are some general ranges for frequency of estrous cycles:

  • 4 to 12 months
  • 5 to 8 months (average)
  • 8 to 12 months
  • 12 to 16 months

Since dogs in heat shed blood and discharge, owners often wish for less frequent cycles. Discuss options with your veterinarian if your dog’s heat cycles are troublesome.

Do Dogs Bleed a Lot When in Heat?

The amount of bleeding during a dog’s heat cycle varies quite a bit between individuals. But in most cases, the discharge is minimal and owners may only notice a few drops of blood here and there.

Here’s a general overview of how much bleeding dogs have while in heat:

  • Days 1-5: Minimal bleeding, just a few drops.
  • Days 5-10: Heavier but not gushing.
  • Days 10-20: Tapering off and darkening in color.

Owners often do not see much blood until day 5-10 when the discharge becomes more noticeable. Monitor your dog closely once she enters the estrus stage when pregnancy risk is highest.

If you see heavy gushes of fresh blood from the vulva at any point, contact your veterinarian. This abnormal vaginal bleeding needs medical attention.

Do Dogs PMS When in Heat?

“PMS” stands for premenstrual syndrome in human females. The equivalent phase in dogs is called proestrus, when eggs in the ovaries start maturing before ovulation. Some owners wonder if dogs experiencing PMS moodiness like women do.

It is true that hormone fluctuations during proestrus can cause behavior changes in dogs. Common signs of canine PMS include:

  • Increased affection and need for attention
  • Restlessness and agitation
  • Changes in appetite
  • Barking and guarding
  • Mounting people or objects

These behaviors are from hormonal changes as the dog’s body prepares for pregnancy possibility. As long as she is not showing aggression, the best thing owners can do is stay patient and minimize stress.

Try engaging your dog in playtime and provide plenty of walks and exercise during the proestrus stage. This can help stabilize her mood until the hormone surge ends.

Do Dogs Need Pads or Panties in Heat?

Dogs tend to be fastidiously clean creatures and most will lick themselves to hide any discharge during their heat cycles. But some leakage inevitably still happens.

Doggy diapers and pet pads can help manage messes and prevent stains while your dog is in heat. They are not an absolute necessity, but they can give owners extra peace of mind.

Disposable dog diapers that attach around the tail base usually stay in place best. Washable cloth panties are a reusable option. Some owners prefer using human sanitary pads inside the diaper or underwear.

When your dog is in heat, confine her to easy-to-clean areas inside your home. Keep her off carpets, beds and furniture unless wearing a diaper to avoid staining.

Do Dogs Have Irregular or Abnormal Heat Cycles?

Most healthy dogs follow a regular estrous cycle after reaching sexual maturity. But abnormalities can sometimes occur including:

  • Silent heats: No external bleeding observed
  • Split heats: Two cycles in quick succession
  • Persistent estrus: Bleeding lasts over 3 weeks
  • Late onset: First heat after age 2 years old

Hypothyroidism, obesity, and reproductive diseases are common causes of irregular cycles in dogs. See your vet if your adult dog has never gone into heat or her cycles seem excessively long, short, or erratic.

At What Age Do Dogs Stop Going Into Heat?

Dogs typically experience estrous cycles throughout their reproductive years. The age when dogs go into menopause and stop cycling varies quite a bit between individuals. But here are some general age ranges:

  • Small breeds – Age 7 to 14 years
  • Medium breeds – Age 7 to 15 years
  • Large/giant breeds – Age 5 to 13 years

As you can see, larger breeds reach menopause at a younger age. Genetics also play a role. Early spaying before first heat can prolong the reproductive lifespan.

Signs that a dog is going through menopause include cycle intervals getting longer and then stopping. Ask your vet if you are unsure if your aging dog has undergone menopause.

Should You Spay Dogs Before First Heat?

Spaying, which is ovary removal surgery, is commonly done before a female dog’s first heat cycle nowadays. Here are pros and cons of early spaying at 4-6 months old:


  • Eliminates heat cycles
  • Prevents accidental pregnancy
  • Reduces some disease risks like pyometra
  • Can slightly prolong the reproductive lifespan


  • Increases urinary incontinence risk
  • May raise orthopedic injury risk
  • Has been linked to some cancers

Talk to your veterinarian about the right age to spay your individual dog based on breed, genetics, and lifestyle factors. Delaying surgery until after 1-2 heat cycles but before full maturity can help avoid downsides.

Can Dogs Get Pregnant at the End of Heat?

Dogs are only able to become pregnant during the estrus stage of heat. This is when they ovulate and have eggs available to be fertilized after mating. Estrus typically lasts about 9 days on average but ranges from 3 to 21 days in length.

Sperm can survive in the female dog’s reproductive tract for up to a week. So pregnancies can result from mating towards the end of estrus since sperm are still present when ovulation occurs.

It is safest to keep male dogs totally separated and avoid breeding ties during the entire 3 weeks that the female’s vulva is swollen. This ensures no unwanted litters will be produced.

Do Dogs Need a Diaper When in Heat?

Diapers are optional for dogs in heat but can make life easier for their owners. Used diapers should be changed 2-3 times per day. Here are some benefits of doggy diapers during estrus:

  • Absorb bleeding/discharge to prevent messes
  • Allow dogs on furniture without worrying about stains
  • Reduce odor from vulvar secretions
  • Indicate to male dogs that mating is not permitted

Reusable cloth diapers with a liner pad are cost-effective if changed frequently. Disposable dog diapers are convenient but generate more waste. Some owners prefer wrapping their dog with a human sanitary pad.

Dogs dislike wearing diapers at first but get used to them. Provide treats and praise when putting on the diaper. Never leave one on for over 8 hours.

Summary and Conclusion

In summary, female dogs do experience recurring estrous cycles similar to the menstrual cycle in humans. Unlike humans, dogs bleed during proestrus before ovulation rather than after. The bloody vaginal discharge signals fertility and prompts mating.

Most dogs reach sexual maturity and have their first heat cycle between 6 months and 2 years old. On average, cycles repeat every 7 months but can range from twice a year to only once every other year. The amount of bleeding varies from barely noticeable to more substantial discharge.

Hormonal changes during heat can cause restless or needy behavior. Pet diapers and pads can help contain the mess. Spaying is an option to avoid dealing with heat cycles. Discuss the right age to spay your dog with your veterinarian.