Dog in Heat: How Long It Lasts, Stages & Signs

As your female puppy grows into adulthood, you may notice certain changes that signal her first heat cycle. For first-time pet parents, a dog in heat can be confusing, especially if you’re unsure what to expect. Going into heat is a normal part of an unspayed female dog’s reproductive cycle. According to Dr. Lindsay Butzer, DVM, this is when estrogen levels rise and then suddenly drop, causing the ovaries to release eggs that can then be fertilized. This is when a dog can get pregnant.

Understanding your dog’s heat cycle (including when it typically begins, how long it lasts, and the physical and behavioral shifts to watch for) can help you prepare, keep her safe, and avoid unintentional pregnancies.

Content:

1. How Long Does a Dog Stay in Heat? Duration, Frequency & the First Heat
2. The 4 Stages of the Dog Heat Cycle
3. Signs & Behavior of a Dog in Heat
4. Caring for a Dog in Heat: Bleeding, Comfort & Keeping Her Safe
5. Spaying, Pregnancy Risk & Male Dogs: Common Questions
6. Conclusion

How Long Does a Dog Stay in Heat? Duration, Frequency & the First Heat

As a pet parent new to a dog’s heat cycle, it’s normal to wonder, “How long does a dog stay in heat?” Figuring out what to do when your dog is in heat for the first time can be puzzling, but understanding what happens during this cycle helps.

When Does the Dog Heat Cycle Start?

The female dog heat cycle starts once she reaches sexual maturity. Usually, this happens around 6 months of age, but it can vary, especially in larger breeds, whose first heat may not start until they’re 2 years old.

How Long Is a Dog in Heat For?

A female dog is usually in heat for 2–4 weeks. It can be shorter or longer for some dogs, but cycles usually become more regular by around 18 months of age.

How Often Is a Dog in Heat?

Female dogs go into heat roughly every 6–8 months for the rest of their lives. However, this can vary depending on a dog’s size and breed. Very small dogs, for instance, may go into heat 3–4 times per year, while giant breeds may experience it only once a year.

Many female dogs have longer gaps between cycles as they get older, but unlike humans, they don’t go through menopause. Meanwhile, spayed female dogs won’t go into heat or get pregnant, as their seasons stop. If your dog isn’t spayed and she misses her heat, contact your veterinarian to help determine the cause and address it early.

The 4 Stages of the Dog Heat Cycle

So what are the 4 stages of a dog in heat? And what happens when a dog is in heat?

The Estrus Cycle

The female dog heat cycle is also known as the estrus cycle, and it covers 4 key stages. Once she reaches sexual maturity, your female dog will always be in one of these stages.

Below are the dog heat cycle stages, or the estrus cycle in technical terms.

1. Proestrus Stage

This is the first stage and lasts 3–19 days. During this time, your female dog’s body is getting ready to mate, so signs such as a swollen vulva and bloody discharge appear. However, she isn’t ready to mate just yet. Instead, you may notice her holding her tail between her legs, or she may sit down when male dogs approach.

2. Estrus Stage

This is your dog’s most fertile phase, when mating is most likely to happen. It usually lasts about 9 days, but can be as short as 3 days or as long as 21 days. At this stage, you may notice your female dog courting male dogs and getting very friendly, with her tail swishing to one side.

3. Diestrus Stage

During this period, your dog’s fertile window has closed, so she’ll either return to her normal behavior or a pregnancy will develop. The swelling and discharge stop, and she won’t show interest in a male dog’s advances.

4. Anestrus Stage

Also known as the cycle’s “resting stage,” anestrus is the last stage of the estrus cycle. If your dog isn’t pregnant, she will stay in this stage until a new cycle starts. If she does get pregnant, this stage begins after she gives birth. Most female dogs come back into heat about 4–6 months after giving birth.

Signs & Behavior of a Dog in Heat

How can you tell if a dog is in heat? The signs and behaviors of a female dog in heat can vary from one dog to another. Becoming more aware of your dog’s heat cycle helps you prepare for changes in her behavior and physical signs.

Position of Tail

Early in the heat cycle, one sign you might notice is your female dog holding her tail between her legs. She does this to shield herself from male dogs’ advances because she isn’t ready to mate just yet. As her cycle progresses, however, she will often start swinging her tail to the side, signaling that males are more than welcome.

Behavioral Changes

You may also notice behavioral changes when a dog is in heat. Common behaviors of a female dog in heat include nervousness or agitation, so she may also show signs of aggressive behavior toward other pets or humans. On the other hand, she may become extra friendly or affectionate.

In a Reddit discussion in r/dogs, the author shares her experience with her dog’s first heat cycle, noticing behavioral changes such as being whiny, clingy, restless, and cuddly. Others agree, and some share their own experiences. For instance, one pet parent says her dog pulls on the leash during walks because she gets excited about meeting other dogs. Another pet parent shared that his dog became snugglier and sleepier than usual. One also shared that her dog is hyper-aware of everything during walks.

Male Attention

One of the things you’ll likely notice when your dog is in heat is the attention she gets from unneutered male dogs everywhere. In the latter part of her cycle, she may even go looking for males herself. She may also try to mount other dogs and random objects.

Swelling and Bleeding

A dog’s vulva may look swollen and more noticeable while she’s in heat. Bloody discharge is also likely, so some spotting on bedding is to be expected. The bleeding usually lasts 7–10 days and tends to become lighter and more watery as she moves into her fertile phase.

Increased Urination

An increase in urination is also likely, as her urine signals to males that she’s ready to mate.

Caring for a Dog in Heat: Bleeding, Comfort & Keeping Her Safe

When it comes to taking care of a dog in heat, you may be wondering what to do when a dog is in heat, how to comfort her, how to manage the bleeding, how to supervise her around other dogs and people, and how to prevent pregnancy, among other things.

Below are some tips to help you care for your dog during her heat cycle:

• Avoid taking your dog to dog parks or similar places where she’s likely to encounter intact male dogs.
• While she’s in heat, keep her on a leash during walks.
• At home, you may use a diaper to help manage her discharge and reduce the mess. Choose one that is absorbent, comfortable, leakproof, and secure. Change her diaper every 3–4 hours to prevent infections and maintain good hygiene.
• If you have male dogs at home, keep them separated from your female dog in the meantime to prevent pregnancy. Gates, crates, and closed doors can help.
• Reassure and comfort your dog as much as you can. A Petcube Cam, for instance, has 2-way audio that lets you talk to your dog while you’re away. The camera can also help you monitor her behavior and confirm that she’s safe at home.
• Keep track of her cycle. The Petcube App lets you log when her heat starts and ends, along with any changes in her behavior or symptoms, so you can spot her pattern and plan ahead for next time.

To prevent your dog from getting pregnant while she’s in heat, close monitoring and supervision are essential. Dogs can go out of their way to find a mate when they’re in heat, so it’s best to be vigilant.

If you don’t intend for your dog to have puppies, spaying is an effective, safe, and permanent way to prevent unplanned pregnancies, and it helps reduce pet overpopulation too. When a dog is spayed, her ovaries and/or uterus are removed, so she can’t get pregnant.

Spaying, Pregnancy Risk & Male Dogs: Common Questions

Can a dog get pregnant when not in heat?

Because ovulation only happens during the fertile window of the heat cycle, dogs can’t get pregnant when they’re not in heat.

Can you spay a dog in heat?

You may be wondering, “Can a dog be spayed while in heat?” Technically, yes, but most veterinarians recommend waiting until your dog’s heat cycle is over. The reasons include:

1. There is an increased risk of bleeding, since the blood vessels near the ovaries are swollen at this time.
2. Added costs, since the surgery and recovery become more complex.
3. She may still attract males for 10–14 days after the spay procedure.
4. Sudden drops in hormones may lead to anxiety, mood swings, and other changes.

Does a dog have to be in heat to get pregnant?

Yes. Pregnancy can only happen when there’s ovulation and the release of eggs, which only occurs during estrus, or the heat cycle.

How far can a male dog smell a female in heat?

In ideal conditions, a male dog can smell a female in heat from up to 5 kilometers (about 3 miles) away. How amazing is canine olfaction?

How long after a heat cycle can a dog be spayed?

It’s best to wait about 1–2 months after your dog’s heat cycle ends before having her spayed. This gives her reproductive hormones and blood vessels time to return to normal, which lowers surgical risks and helps prevent false pregnancies.

Conclusion

Your dog’s heat cycle may seem confusing at first, but understanding how it works helps you prepare when your dog goes into heat, especially if it’s her first. If you don’t intend for your dog to have puppies, spaying is the most effective and safest way to prevent pregnancy. With guidance, monitoring, and the right tools, you’ll be able to make more informed decisions about your dog’s reproductive health.