Understanding your dog's natural cycles can feel like a puzzle at times, especially when it comes to their heat cycles.

Whether you're a new dog owner or an experienced one, knowing the ins and outs of a female dog's heat cycle can be crucial for her health, behavior, and potential future as a mom.

So, how long are dogs in heat, exactly? Are there signs you should look for? And how should you care for your dog during this time?

Key Takeaways:

  • A dog's heat cycle, also known as the estrous cycle, typically lasts between 2 to 4 weeks and generally happens twice a year.
  • It involves four stages: proestrus, estrus, diestrus, and anestrus.
  • Keeping your dog comfortable and maintaining hygiene during her heat cycle is important. This includes limiting her interactions with male dogs to avoid unwanted pregnancies.

In this blog post, we'll demystify the heat cycle, explore its stages, and provide you with the insights you need to navigate this essential part of your canine companion's life.

How Long are Dogs in Heat? 

A dog's heat cycle, also known as the estrous cycle, typically lasts between 2 to 4 weeks. There are four stages in a dog's heat cycle: proestrus, estrus, diestrus, and anestrus.

Stages of a Dog's Heat Cycle

Each stage represents a period of time before, during, or after a dog is in heat. Let's take a look at each heat cycle stage in detail:

1. Proestrus

This is the beginning of the heat period where your dog's body prepares for pregnancy. The dog may have a bloody discharge and swelling of the vulva, but she will not yet be receptive to males. This stage lasts approximately 9-10 days.

2. Estrus

During this stage, the dog is receptive to mating with males. The discharge may change from bloody to a yellowish color. This is the time when ovulation occurs. This stage also lasts about 9-10 days.

3. Diestrus

This is the stage following estrus. Whether the dog is pregnant or not, this stage lasts about 60-90 days. If the dog has become pregnant, this is the stage where she'll carry her puppies. If she's not pregnant, her body will act as though she is.

Related reading: How Long are Dogs Pregnant?

4. Anestrus

This is a period of inactivity between heat cycles, and it lasts until the next heat cycle begins. This is usually about 4-5 months.

Keep in mind that these times can vary, and different breeds may have slightly different lengths of heat cycles. Always consult with your vet if you have any concerns or need advice.

Signs Your Dog is in Heat

Recognizing the signs that your dog is in heat can help you manage her behavior and health during this time.

Here are some of the most common signs:

  • Swelling of the Vulva: This is one of the first signs that a dog is going into heat. You may notice that your dog's vulva is swollen or larger than normal.

  • Vaginal Discharge: At the beginning of the heat cycle, the discharge is often bloody. As the cycle progresses, the discharge usually changes from bloody to a clear or straw-colored fluid.

  • Increased Urination: Your dog may urinate more frequently than usual. This is her way of leaving a scent for male dogs to let them know she is in heat.

  • Change in Behavior: Dogs in heat might show behavioral changes. They can become more affectionate or clingy, or alternatively, they may seem more restless or anxious. Some may show aggression.

  • Flagging: This is a term used to describe a specific behavior where the female dog raises her tail base up and to the side.

  • Attraction of Male Dogs: If male dogs are suddenly more interested in your female dog, it could be a sign she's in heat. Male dogs can detect a female in heat from quite a distance.

Remember, each dog is unique and may not show all these signs. If you're unsure about whether your dog is in heat or if you have concerns about her behavior or health during her heat cycle, it's best to consult with a vet.

Veterinarian Tips for Managing a Dog in Heat

Managing a dog in heat requires a bit of patience and understanding as your dog navigates this natural part of her life. Here are some practical tips:

Keep Her Inside

When your dog is in heat, she'll be emitting pheromones that can attract male dogs from quite a ways away. To avoid unwanted attention (and potential pregnancies), it's best to keep her indoors as much as possible during her cycle.

Supervise Outdoor Trips

When she needs to go outside, ensure she's supervised at all times to prevent unwanted mating.

Use Doggy Diapers

Doggy diapers can help manage the vaginal discharge and keep your home clean.

Keep Her Comfortable

Some dogs may experience discomfort or restlessness during their heat cycle. Provide a comfortable, quiet place for your dog to relax.

Don't Neglect Exercise

Regular exercise with your dog is still important during this time, but try to do so in a controlled environment. Avoid dog parks or other places where off-leash dogs may be present.

Watch for Signs of Complications

While most heat cycles go smoothly, complications can occur. If you notice excessive discharge, behavioral changes that concern you, or signs of illness, contact your vet.

Consider Spaying

If you're not planning to breed your dog, consider having her spayed. Spaying eliminates heat cycles and can also prevent certain health problems.

Related reading: Spaying a Dog: Everything You Need to Know

Common Health Issues During a Dog's Heat Cycle

Similar to humans, ovarian cycles in dogs might come with some complications. Here are a few of the more common health problems dog owners might come across when their dog is in heat:

1. Pyometra

Pyometra is a serious, potentially life-threatening condition where the uterus fills with pus. It typically occurs in the weeks following a heat cycle, particularly in dogs who did not become pregnant. Symptoms can include increased drinking and urination, lack of appetite, vomiting, and lethargy. Emergency veterinary care is required.

2. Metritis

This is an inflammation of the uterus that can occur after a dog has given birth or had a miscarriage. Symptoms can include fever, lethargy, loss of appetite, and a foul-smelling discharge. This condition also requires immediate veterinary attention.

3. False Pregnancy

Sometimes, after a dog has gone through a heat cycle, she might exhibit signs of pregnancy even if she is not actually pregnant. This can include weight gain, enlargement of the mammary glands, nesting behavior, and even phantom labor. While false pregnancy is usually not harmful, it can be distressing for the dog.

4. Mammary Gland Tumors

Unspayed female dogs who go through heat cycles are at a higher risk of developing mammary gland tumors, which can be benign or malignant. Regularly checking your dog for lumps and bumps can help with early detection.

5. Ovarian and Uterine Tumors

Although less common, intact female dogs can develop tumors in the ovaries or uterus.

Regular vet check-ups and maintaining open communication with your vet can help catch any potential issues early.

Frequently Asked Questions

What age does a dog come into heat?

Most female dogs will have their first heat cycle between six and nine months of age, but this can vary depending on the breed and size of the dog. Small dog breeds may go into heat for the first time as early as four months old, while large and giant breeds may not have their first heat until they are 18 to 24 months old.

How often are female dogs in heat?

The heat cycle, also known as the estrous cycle, usually occurs approximately every six months, but this can also vary widely between individual dogs and breeds. Some dogs may go into heat only once or twice a year.

How can you tell when your female dog is ovulating?

A veterinarian can perform pet blood tests to tell you when ovulation has occurred. This can help you to manage breeding dates for increased chances of success.

How can I stop my dog from coming in heat?

Surgical sterilization, also known as a spay procedure, is the most effective way to stop your dog from coming into heat. This is an operation that removes the ovaries and uterus, so your dog can never become pregnant.

Do female dogs go through menopause?

Older female dogs do not go through menopause as humans do. They will continue to come into heat, but you may notice the intervals between their heat are longer or more unpredictable.

What are other terms for a dog in heat?

Coming into heat, being in season, or estrus are all ways of saying your dog is in the fertile window for breeding and how long are dogs in heat often depends on their breed.


It varies how long dogs are in heat, but all dogs do experience a heat. If your dog reaches 3 years old and hasn’t had a heat yet and you are wanting to breed, you should reach out to a veterinarian for advice

A dog in heat is a completely natural process, although for the new dog owner it can be a bit overwhelming and messy. The easiest way to prevent stress for you, and unwanted pregnancies for your dog, is to spay her. Not only does this take away her ability to breed, but protects her against other harmful conditions like uterine infections and cancer, which can both be life threatening and very expensive to treat.