Female dogs that haven’t been spayed will generally have their first heat when they’re six to twelve months old. Then, they’ll go into heat again every six months on average. This is the time when your dog could mate and get pregnant.1 So it’s very important to be aware of the most common signs and behaviors of a female dog in heat, especially if you want to prevent an unplanned dog pregnancy.

Discover the top 14 dog in heat symptoms below, so you’ll be prepared!

When do dogs go into heat?

Female dogs have their first heat cycle when they reach puberty: the time when they become sexually mature and capable of reproducing. This usually happens around six months old, but the exact age can vary by breed.

Small dogs are known to start their estrus cycle earlier, whereas large or giant breeds may not have their first heat until they are 18 – 24 months1.

Heat and breeding in domesticated dogs can happen any time of year – they’re not associated with any particular season. The only exception is Basenjis and Tibetan Mastiffs, who tend to go into heat in spring.

How long does a dog stay in heat?

Dogs are usually “in heat”, or in the estrus phase of the dog heat cycle, for 3-21 days. On average, it lasts about 9 days.

Read More: How Long Is A Dog In Heat? The Dog Heat Cycle Explained

Common behaviors of a female dog in heat

1) Swelling of the vulva

One of the most noticeable physical signs of a female dog in heat is a swollen vulva (the outer part of the vagina). This usually happens during the early phase of her cycle. The amount of swelling varies among dogs; it’s more noticeable on some dogs than others.

So if your female dog’s genitals seem bigger than usual, she may be in heat.

2) Discharge and bleeding

Another obvious sign of a female dog in heat is a red, bloody discharge. This bleeding happens at the same time as the swelling; during the proestrus or first phase of the dog in heat cycle.

dog in heat cycle infographic - proestrus, estrus, diestrus, anestrus by illustrated by tractive

During this time you might observe a light to moderate amount of vaginal discharge, which can range in color from pink to reddish-brown. Like swelling, the amount of bleeding also varies by dog. But typically bleeding is light during the first few days and grows a bit heavier mid-week.

3) Excessive licking

It’s normal for dogs to keep themselves clean and tidy by licking themselves. But if you notice your female unspayed dog licking her private parts excessively, it’s a good indication that she may be in heat!

A female dog will lick herself in response to the swelling of the vulva and bloody discharge she experiences as a part of her reproductive cycle. Most dogs can keep themselves clean during this time.

If your dog’s discharge is making a mess, you may want to consider using a heat diaper and/or dog wipes.

4) Tail tucking

Another sign of a dog in season is tail tucking. Your dog may hide her tail between her legs during the early phase of heat. This is her way of guarding her private area before she’s ready to mate.

dog laying in grass outside being pet by a woman

5) Seeking more attention

Many dogs in heat crave extra affection from their humans. You might find that your normally independent dog suddenly wants to be close to you more often, leaning in for pets or cuddles. This desire for comfort is typical and is a great opportunity to reassure her.

6) Changes in urination behavior

A female dog who is ready to mate often urinates differently, so that’s another clue that your dog is in heat. This could mean:

  • Urinating more often than usual
  • Raising her leg differently while urinating – or when she sees a male dog
  • Frequently urinating around male dogs

This behavior is her way of marking territory, spreading her scent as a way to signal potential mates that she’s ready to breed. It’s common for her to lift her leg more often or even pee in small amounts during walks.

So if your dog’s peeing habit is suddenly not as predictable as normal, she might be in heat.

7) Change in activity levels

Another dog in heat symptom to look out for is changes in activity levels. It’s common for female dogs in season to be hyperactive, restless or agitated. So don’t be surprised if your dog is more active than usual. She may have trouble settling down and might pace around more than usual. These behaviors are normal and often indicate that she is feeling anxious due to her hormonal changes.

On the other hand, some dogs might be very tired during this time.

Dog wearing white Tractive GPS Dog Tracker outside in a field, Tractive GPS app screens in the foreground

Since changes in sleep and activity levels in your dog can also indicate a health issue, it’s a good idea to monitor your dog’s activity with a GPS and health tracker for dogs.

Tractive GPS Dog Health Tracker

With a Tractive GPS Dog Tracker, you’ll receive Health Alerts if something seems off with your dog’s activity. Not to mention, you’ll be notified if they leave the Virtual Fence – so you can start LIVE Tracking them.

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8) Attention from male dogs

Male dogs are biologically hardwired to seek out a female dog in heat. This is because of the pheromones she releases, which act like an open invitation to nearby males. So if your girl dog is getting a lot more attention from male dogs than usual, she may be in season.

Even neutered male dogs may still try to mate with a female. So keep a close eye on her when outside to prevent any unwanted encounters. Otherwise an unsupervised female dog in heat could end up (unexpectedly) pregnant.

9) Change in posture & tail position

When female dogs enter the estrus (second) phase of the dog in heat cycle, they’re ready to mate and they show this with their posture and tail position. Your dog make take a suggestive posture, as an invitation to male dogs. You’ll also see her raise her tail slightly and move it to the side – this position becoming even more pronounced when she’s touched.

10) Mounting and humping behavior

Female dogs in heat may mount, hump or thrust when they’re ready to mate – it’s not just male dogs. She may try to mount other dogs, people, or even soft toys. While it might be surprising to see, this is a natural way for her to relieve some of the tension she is experiencing.

two dogs outside sniffing each other with leaves on the ground

11) Getting friendlier with male dogs

Another big clue that your dog is in heat is when she starts to become more receptive and friendly to male dogs. For example, during heat she may let male dogs sniff and lick her vulva, when normally she would not tolerate this behavior.

Excessive tail wagging is another a sign of openness towards male dogs, signaling that she welcomes physical contact.

12) Escape attempts

The mating instinct is one of the most common reasons why dogs run away. So if your canine friend is attempting to run away or escape the yard, she may be in heat. Since dogs are more hyperactive and distractable during this time, it’s a good idea to do the following to keep your dog safe:

  • Microchip your dog
  • Invest in a good GPS dog tracker
  • Keep your dog in heat on the leash
  • Consider spaying your dog to prevent incidents

Since dogs in heat can be stubborn, they may be less likely to return to you when called.

13) Changes in appetite

A dog in heat might also eat less or, conversely, become hungrier than usual. Both increases and decreases in appetite are common during the heat cycle and often vary depending on the individual dog.

Make sure to monitor her eating habits and provide balanced meals to keep her healthy.

Read More: Dog Won’t Eat? 6 Common Causes For A Dog Not Eating

14) Anxiety, agitation and nesting

Finally, a female dog in heat may become anxious or even aggressive during the time she’s open for mating. Commonly she’ll also display nesting behaviors, in preparation for pregnancy.

How to care for a dog in heat?

With all the hormones and strong instincts going wild, it can sometimes be challenging to care for your furry friend in heat. Experts recommend using both a microchip and a GPS dog tracker (as well as the leash) to keep your dog safe. You may also want to consider spaying your dog so she doesn’t go into heat again.

Check out our guide to caring for a dog in heat for tips and information on how to navigate this phase in your dog’s cycle.

Conclusion

It’s usually not too difficult to spot a female dog in heat – these common behaviors and signs can be a big clue that your canine friend is in mating season. She may be more active and restless than usual, try to escape more often, and act differently towards male dogs. Now that you know the typical dog in heat symptoms you are better prepared to take care of your furry family member during this time.