When Do Labs Go In Heat?

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Key Takeaways

  • A female Labrador will go into heat between six and twelve months, and in most cases, it happens after nine months.
  • Labradors go in heat twice per year or roughly every six months.
  • When a lab is in heat, they will have significant behavior changes, bleeding, and a swollen vulva.

All female labs will experience a cycle known as heat when they get old enough. This can lead to a litter of puppies, so knowing when it happens is critical.

Labs go into heat after 6-12 months; for most of them, it happens around the nine-month mark. The heat cycle happens in four phases, and the initial heat cycle will last about two to four weeks, and it occurs roughly twice yearly every six months unless the dog gets spayed.

Raising a young female Labrador is a different experience compared to a male because of the heat cycle. We intend to simplify this experience by explaining when the dog will go in heat and how to handle it properly.

In this article

When Do Labs Go In Heat?

Like all other dogs, labradors enter a period called "heat" or "estrus" when they are sexually mature and ready to breed. This happens after 6-12 months; the first heat cycle lasts about two to four weeks.

During this time, female Labradors will experience several physical and behavioral changes. They may have swelling and discharge from their vulva and may exhibit behaviors such as vocalizing, restlessness, and an increased interest in male dogs.

Owners of female Labradors need to be aware of these changes and take steps to manage them. This can include keeping the dog away from male dogs, providing them with a clean and comfortable place to rest, and monitoring their behavior for any signs of distress.

Owners also need to have their dog spayed if they do not plan to breed her. This simple surgical procedure can prevent unwanted pregnancies and help protect the dog's overall health.

Understanding the heat cycle and taking appropriate steps to manage it can help ensure the health and well-being of your female Labrador.

How Long Are Labs In Heat?

Female Labradors experience a period known as "heat" or "estrus" when they reach sexual maturity. This is when they become receptive to mating with male dogs and can get pregnant.

The length of time that a Labrador stays in heat varies, but it typically lasts for about two to four weeks. The cycle occurs in four distinct phases too.

The first week of heat is known as the proestrus stage, during which the female dog may have a swollen vulva and a bloody vaginal discharge.

The second week is the estrus stage, during which the female dog is most receptive to mating with male dogs. This is the time when she is most likely to get pregnant.

The third week is the diestrus stage, during which the female dog's hormones return to normal. She may still have some swelling and discharge, but it will be less noticeable than during the first two weeks.

Generally, two to four weeks is the average heat cycle length. We will explain each of these phases in-depth below.

Labrador Heat Cycle Explained

As mentioned, there are four phases to every heat cycle for a female Labrador. Each cycle lasts a few days up to two weeks, depending on the dog.

When this cycle begins, significant hormonal changes are happening in the Labrador. This is especially true for the first heat cycle, which will repeat every 6-9 months after that.

Proestrus Stage

The initial heat cycle stage is the proestrus stage. In rare cases, it will last as little as four days or as long as 21 days when all of the apparent signs indicate the heat cycle has started.

This includes a swollen vulva, bleeding, increased male attraction, mood changes, increased self-grooming, etc. Be aware of these signs and keep an eye out for them to identify when the lab enters the heat cycle.

Estrus Stage

Next, the Labrador will enter the estrus stage, which lasts about 5-15 days. This is the primary or heat stage of their cycle when ovulation occurs, and the dog is finally ready to mate.

In this stage, the dog is likely to seek out other male dogs, and the flagged tail is typical. This is when they raise their tail and stop hiding their vulva, indicating they are ready to mate.

Diestrus Stage

Following the mating period in the estrus stage, the Labrador experiences a rest period known as the diestrus stage. This lasts roughly two months, and the fertile and reproduction window has closed.

Anestrus Stage

Next, the anestrus stage occurs after the resting period concludes. This is the final heat cycle stage, and it lasts for about 90 days as a way for the Labrador to prepare for the new, upcoming heat cycle.

This is also the only time a female Labrador should be spayed. It’s necessary to allow the first heat cycle to happen. Then during this stage, the dog can get fixed to avoid any problems in the future.

How Do You Know When A Lab Is In Heat?

It's essential to be aware of the signs that a Labrador is in heat. By keeping her confined and clean and watching for signs of infection, we can help ensure that she stays healthy and happy during this time.

Some of the obvious signs include bleeding, significant changes in behavior, or body changes like a swollen vulva. We will explain how to identify each of these signs below.


A female Labrador in heat may have a bloody discharge, so keeping her clean is critical. However, this will vary with each dog; some may have only a drop or two of blood that goes unnoticed.

One way to avoid missing this while keeping it under control is with dog diapers. It keeps the blood off the floors and allows us to identify when our dog is in heat.

Significant Behavioral Changes

A Labrador will experience significant changes in behavior during this cycle. She may become more affectionate and attentive to her owners and may also exhibit increased energy levels and activity.

The dog will also start self-cleaning much more than usual. They also act more clingy and sleep increases slightly with more restless behavior.

Swollen Vulva

The obvious way to tell if a lab is in heat is by looking for signs of a swollen vulva. This is the easiest way to spot whether the cycle has begun because it’s significantly larger than normal.

The swelling will make it easier to see, and even with no previous experience spotting this condition, it would be hard to miss.

How Often Do Labs Go In Heat?

Labradors typically go into heat twice a year, with the first heat typically occurring when they are between six and nine months old. This cycle continues roughly once every six months for the rest of their life.

During the heat cycle, a female Labrador will experience several changes in her behavior and appearance. The heat cycle typically lasts 2-4 weeks, during which the female Labrador will be receptive to mating.

Labradors must go through regular heat cycles, which is a normal and healthy part of their development. If a female Labrador does not go into heat, it could be a sign of a health problem, and a veterinarian should see her.


Mark Brunson

Mark Brunson

Mark is the founder of Everything Labradors and a husband and father of 3. He enjoys spending time with his family, including his dog Molly, a Labrador/Golden Retriever mix. He’s a big fan of the outdoors and loves to travel to new places.

Read more about Mark Brunson