Dog Heat Cycle: A Comprehensive Guide for Pet Owners

Is your dog in heat? Most non-spayed female dogs come in heat twice a year once they reach their sexual maturity. Once you learn to recognize the first symptoms, you must be careful to avoid an unwanted pregnancy.
We have many a new pet parent come into our veterinary practice with their girl puppy confused. Their four legged fur baby isn’t spayed yet and they are concerned about their dog health. We teach them the basics of their dogs heat cycle, also known as the estrus cycle. This is when their dog becomes sexually mature and is receptive to mating. We found that understanding this process is important for pet owners so they can care for their dog needs. After teaching countless new dog owners, we decided to write this comprehensive guide which connects to the other 15 articles we’ve written on the dog heat cycle topic.

In this comprehensive guide, you’ll learn all aspects of the dog heat cycle, what it is, its causes, symptoms, and how to care for your dog during her heat. If you have a specific question, please check our FAQ article which may be the easiest way to your answer.

Yellow female lab smiling outside.
Can you care for me during the my dog heat cycle?

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Table of Contents

Dog Heat Cycle Infographic explaining the 4 stages & how long each stage lasts.1. Proestrus stage2. Estrus stage3. Anestrus stage4. Diestrus stage
Dog Heat Cycle Infographic

What is the Dog Heat Cycle?

It’s the reproductive cycle that female dogs go through. During this time, a female dog’s body prepares for pregnancy and produces eggs that are ready to be fertilized. During this time, the female dog may exhibit certain signs and behaviors that indicate she is in heat.

What are the 4 stages of a dog in heat?

  1. Proestrus stage: The preparatory stage. Bloody vaginal discharge may occur. Lasts 7-10 days
  2. Estrus stage: Mating period. Receptive to mating, pregnancy can happen. Lasts 5-10 days.
  3. Diestrus stage: Supports pregnancy. If not, rest & recovery. Lasts 10-140 days.
  4. Anestrus stage: Downtime between heat cycle. Lasts about 6 months.

For more detail on each of the stages, please refer to our article which has much more information on What are the 4 stages of the dog heat cycle. One common question our patients parents ask is how to tell when their dogs heat is over. For details on this, we refer them to our article How to know when your dog’s heat is finally over.

How long do dogs stay in heat?

21 days. On average, the dog heat cycle last 2 to 4 weeks. The estrus cycle typically occurs twice a year. A smaller dog breed can cycle 3 times per year. Larger dog or giant breed can cycle only once per year. At the beginning of the heat, there is a period called “proestrus” – a time before ovulation in which female cannot get pregnant and won’t let a male jump on her. There are 2 main parts of the dog heat cycle that we’ll discuss next.

Proestrus: Lasts for 3 to 17 days

Proestrus usually lasts about nine days. Unfortunately, you can’t tell for sure when it ends. Your girl becomes willing to breed, as proestrus may be as long as 17 days and as short as 3 days. This means that you can’t take a break and you have to watch after your girl from the first day you notice she’s in heat. One of the first signs of heat is yellow or red discharge from the vulva. If you notice it, time to prepare yourself. You’ll have to guard your girl against males. One of the biggest challenges will be keeping her (and yourself) sane. Luckily, you can learn how to calm a female dog during the heat here.

Estrus or Standing heat: Lasts for 7 to 9 days

After proestrus comes the second phase of the heat period, estrus. Sometimes it’s called a “standing heat” because it starts when your female is willing to breed and stands up when a male is trying to mount her. Estrus ends when she doesn’t stand anymore. Simple, right? Well.

Female dog allowing a male to mount her during estrus
If she’s receptive to mounting, she is in Estrus.
Photo by resakse, cc

On average standing heat lasts for seven to nine days. Note that it can be as long as 20 days if it starts early in the heat period.

The beginning of standing heat can be confirmed only by your veterinarian. However, you can try to rub your dog’s back and see if she’ll stay standing up or sits down. If she stays standing, then obviously she is in the standing heat.

When standing heat begins (remember that without tests made by a vet, you can’t tell for sure), there are usually one or two days until ovulation. That is the beginning of the part of the dog heat cycle when your female dog can get pregnant.

This period continues during the whole standing heat. However, the most fertile days are when your dog is ovulating and the first days are right after it. So this is the best time when you should breed her or be extra cautious to avoid unwanted pregnancy.

It ends when a female dog refuses to stand for mating. Male dogs now lose their interest in her as well. And this is when you can get back to normal life.

While most dogs go into heat twice a year and it lasts for 21 days, abnormal dog heat cycles can occur. We explains the different abnormal estrus cycles in our article Abnormal heat cycles in female dogs.

When do dogs go into heat?

6 months. The first heat for a female puppy will have her first heat at 6 months on average. This assumes she isn’t spayed before then. We recommend spaying surgery to new female puppy owners when she’s old enough. We do this because there is evidence that this eliminates her chances of getting mammary cancer. For more information, please refer to our article At what age do dogs go into heat for the first time.

The dog heat cycle is controlled by the release of hormones in the female dog’s body. These hormones trigger the release of eggs and get her body ready for mating. The exact trigger for the dog heat cycle isn’t fully understood, but it is believed to be influenced by things such as age, weight, and genetics. We wrote an in depth article on the hormones your dog is affected by in How hormones regulate the heat cycle of female dogs. In general, female dogs reach sexual maturity between 6 and 12 months of age. A larger dog may take longer to fully mature than a smaller dog. Their heat cycles will continue until they are no longer able to breed or until their bodies naturally stop producing hormones. To learn how often you and your female dog will have to deal with her estrus cycle, please refer to the section How many times a year is a dog in heat? in our article How old is a dog when they go into heat?

If you’d like to know when your dog will come into heat or when her heat will end, or you need a dog heat cycle calculator, please refer to our article How to know when your dog will come in heat.

Dog in heat symptoms

The symptoms of the dog heat cycle can vary from dog to dog but there are some common ones that pet owners should be aware of. The most common signs of the dog heat cycle include:
Bleeding: The most obvious sign of the estrus cycle is bleeding from the vagina. This is the shedding of the uterus lining and is a sign that your dog is in heat. There’s a common belief that your dog can’t get pregnant while bleeding which is not true. For an in depth look into this subject, refer to our article Can a female dog get pregnant while bleeding?
Swelling of the vulva: Another common sign is swelling of the vulva. This is increased blood flow to the area and can be a sign that she is ready to mate.
Increased urination: Dogs in heat pee more because their bodies produce more hormones and increase blood flow to the area.
Increased aggression: Some dogs may be more aggressive during their heat cycle because of hormonal changes and may be more nervous and irritable.
Increased affection: Some dogs may become more affectionate during their heat cycle. They may seek more attention and affection from their owners.

These are the most common symptoms. For an in depth look at what to expect, please refer to our article Symptoms of a dog in heat.

How to calm a dog in heat

We also spend time with our patients owners on how to care for their dogs during the heat cycle. Your dog may experience pain and discomfort during her heat. For more details on this and how to deal with it, read our article Do dogs get period cramps? How to calm & soothe a dog in heat. Here are our top tips for caring for your dog during her heat cycle:
Provide a safe and secure environment: It is critical to keep dogs in heat in a safe and secure environment to prevent an unwanted pregnancy. You’ll want to supervise your dog when she’s outside so she doesn’t come into contact with any male dogs. If like us, you have male dogs in the house or nearby, here’s our article How to calm a male dog when your female dog is in heat.
Give a healthy diet: Dogs in heat need a healthy diet to support their bodies. Plan on providing your four legged fur baby with high quality dog food and plenty of fresh water.
Lots of exercise: Exercise is important for dogs in heat. It helps reduce stress and anxiety. However, be careful not to over exercise her to the point of exhaustion. You can take your dog for walks but there are things to be aware of so please read our article on Walking a female dog in heat.
Keep her clean: Your little girl may have vaginal discharge which can be uncomfortable for them. If she doesn’t clean herself, you should clean her regularly to prevent infections and ensure their comfort.
Use dog diapers: Dog diapers can be a useful as they can prevent vaginal discharge getting on your furniture and carpet.
Consult your Veterinarian: If you have any concerns about your dog’s health please talk to your veterinarian. Your veterinarian can provide guidance on how to care for her. This is critical if your goal is to have a litter of puppies. Your vet can guide you and make sure she is healthy through to delivery. On the other hand, if you and your vet agree, you can stop her cycle. Read more on this topic in our article How can you stop a dog from being in heat.

When to breed a dog in heat

We council our pet parents to carefully consider if they want to breed their dog during the estrus cycle. Breeding should only be done with careful consideration and planning. We spend a lot of time working with pet shelters in our area and we can’t more strongly recommend not to breed your pets. In our case, we bred our first male as he was a purebred from champion lines and breeding was a condition of us getting him from the breeder. We happily welcomed his son as our reward for years of dealing with his hormone filled antics. He really went crazy at times, so we wrote an article Do male dogs go into heat. Again, if this isn’t the case with your pets, please refer to our article about dog spaying and neutering, Does fixing a dog calm them down? .

If you are considering breeding your dog, please develop a thorough understanding of the breeding process and the responsibilities that come with it. You’ll also want to ensure you have a healthy and well bred male dog to mate with your female dog. Most importantly is to ensure both dogs have no current or history of genetic or health problems can lead to serious issues for the puppies. These are things like hip dysplasia and allergies. It is crucial to consult with your veterinarian and have regular check ups to ensure the health and safety of both the mother and her puppies.

How do I know when my dog is out of heat?

It’s a risky business guessing when your dog’s heat is finally over. If you decide that your dog has finished her season a day too early, all your efforts to keep her safe might be in vain which you definitely don’t want.

Note, while the only way to confirm where your dog is in her cycle is vaginal cytology, a test done at your veterinarian’s clinic. It’s rarely necessary however. A dog’s heat follows a specific pattern and if you follow the signs, you won’t get lost.

We mentioned earlier that not all dogs show symptoms when in heat, but most commonly do. The easiest way to tell when your dog is done with her heat is to look for them. Meaning, look for the absence of symptoms.

Remember that there are a set of signs telling the dog is in heat. Lack of one of them tells you nothing (for example, swelling of the vulva and bloody discharge ends before the heat is over), but if all of them have disappeared, your dog is probably out of the heat.

One of the most popular signs of female not being in heat is a lack of interest in males, though it’s tricky. Her interest doesn’t drop suddenly one day but ceases gradually. You may push or scratch your dog’s lower back. If she’s not “pushing back”, and isn’t flagging her tail to the side, chances are good that your dog isn’t in heat anymore. Another thing is to observe your dog’s behaviorMost females are restless during the heat. This tends to stop as her heat ends. She may start sleeping better and wake you up less often.

You’ll know to pay closer attention to all of this as the calendar marches on. Exceptions of course happen and you shouldn’t consider your dog will be out of her heat after 21 days. However, if you noted when your dog first showed signs of her heat cycle, you can look for changes in your dog as 21st day approaches.

Add some days of safety. After you think her heat is over, stay cautious for a few days after. If you misjudged when your dog is out of the heat, it’ll pay off and won’t do any harm even if you judged correctly. These days will be much more comfortable than the previous few weeks anyway.

Spaying and the dog heat cycle

The majority of dogs we see in our clinic have pet parents that don’t want to breed their dog. We strongly recommend spaying as an option to consider. What is spaying? Spaying is a surgical procedure that removes the ovaries and uterus of female dogs, which eliminates their ability to reproduce.
Spaying has several benefits. They include reducing the risk of certain cancers and eliminating the risk of unwanted pregnancy. It also eliminates the need to care for a dog during her heat cycle. As you’ve read in this guide, it can be a stressful and time consuming process. We’ve had the rare patient that cycled again after her spaying surgery. For details, we wrote this article Is your spayed female dog in heat again?
While it’s a very common and relatively safe, spaying is a major surgical procedure and should be done with careful consideration. Please consult with your veterinarian and discuss the risks and benefits of spaying.


Your dog’s heat cycle is a natural process which allows them to become sexually mature and breed. Understanding this process is important for pet owners, as it can help them provide the necessary care and attention to their dogs during this time.
By reading our comprehensive guide, you’ve learned all aspects of the dog heat cycle, what it is, its causes, symptoms, and how to care for your dog during her heat. As you’ve learned, caring for a female dog in heat can be challenging, but you now know what’s happening and how to care for her. This will go a long way towards a healthy and happy life with your pet dog. And keeping your Pet Happy is what we all want.

Articles on the Dog Heat Cycle

Below is a list of all our articles about female dogs going through their estrous cycle.

Bonus: Dog spaying and neutering. Should you consider it? and Warning signs after spaying a dog.

We do not want to lie. It’s not easy to handle a female dog when she is in heat. Most owners are happy when it all ends. We hope this guide will make things a lot easier for you.

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