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How Long Are Dogs in Heat? Vet-Approved Canine Heat Cycle Facts & FAQ

Dean Eby

By Dean Eby

dog sniffing dog in heat

Vet approved

Dr. Maja Platisa Photo

Reviewed & Fact-Checked By

Dr. Maja Platisa

In-House Veterinarian, DVM MRCVS

The information is current and up-to-date in accordance with the latest veterinarian research.

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Canine mating and reproductive cycles are quite different from our own. For starters, dogs are only pregnant for 9 weeks before giving birth, compared to the 10 months for humans. Additionally, dogs go into heat, which is when they’re fertile and receptive to mating. This is different from a human period, though it’s similar in the sense that it brings along a lot of hormonal changes.

During this time, a female dog can have discharge from her vulva, behave differently, act nervous, and have swollen genitals. Heat sounds like something that you can’t overlook, so how long does it last, and is this something your dog will have to go through for her entire life?

How long are dogs in heat? How often do dogs go into heat? By the end of this article, you’ll have the answers to all these questions, keeping you prepared for your dog’s reproductive cycle.

As a quick answer, dogs go into heat approximately every 6 months, and it typically lasts 2 to 4 weeks.

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How Often Do Dogs Go Into Heat?

Once your dog begins her heat cycles, you can expect the process to repeat approximately every 6 months, meaning she will go into heat twice a year on average. Of course, this is the case for most female dogs; some will have a heat every 5–11 months. There are also a few breed exceptions, such as the Basenji and the Tibetan Mastiff; the females of these breeds are known to cycle once a year.

Heat cycles will continue for your dog’s entire life, though as she gets older, the frequency may decrease while the time between cycles increases.

What Age Do Dogs Start Going Into Heat?

Depending on what breed your dog is, she could experience her first heat cycle at different times. Small breeds sometimes go into heat for the first time at just 5 months of age. That said, the average for most dogs is about 6 months. Large breeds are often on the opposite end of the spectrum, though. For bigger breeds, the first heat cycle might not begin until the age of 12–18 months.

How Long Is a Dog’s Heat?

When your dog is in heat, it can be a bit of a difficult time. You’ll have messes to clean up, and any male dogs in the vicinity will likely be frantic. Fortunately, you won’t have to deal with these concerns for long. For most dogs, their heat lasts about 2–4 weeks.

In the first stage of heat, the female dog will attract males, but she won’t be receptive to them. That said, some dogs are receptive from the start of heat until the end. You’ll know when your dog’s cycle has ended because the bleeding and discharge cease, and male dogs are no longer as attracted to her.

Should You Breed Your Dog?

We can all agree that puppies are super cute. However, they do grow up quickly. An important and complex question remains: Should you breed your dog at all?

Today’s animal shelters are overpopulated and overwhelmed with abandoned and unwanted dogs, many of whom get put to sleep or spend their whole lives in a small cage, not being able to express their normal behaviors or have fulfilled lives. By breeding dogs, we may contribute to this issue of pet overpopulation. Before breeding your dog, consider this crucial ethical aspect, as adopting another dog or a puppy will bring equal joy to your home, and you can make a life-changing difference to that poor pup.

When Can You Start to Breed a Dog?

If you do decide to breed your dog, speak to your vet first to ensure that she is fit and healthy for maintaining a pregnancy. If she has any health issues that may be heritable, she should not be bred, as these will be passed onto her puppies. There are certain breed-specific blood tests and evaluations, such as hip and elbow scores and ocular exams, that every dog should undergo before being considered for breeding, to ensure that they will not put their offspring at risk of any breed-related health issues. This is responsible breeding that ensures the health and welfare of the breed going forward.

Technically, once your dog’s heat cycles start, she’s capable of producing offspring, though it’s not an optimal time to start reproducing. In fact, it’s recommended that you don’t start breeding a dog until after she has completed her third or even fourth heat cycle. Prior to this point, your dog is not fully mature and developed and may have a silent estrus, meaning the signs of estrus are not clear, and breeding may be unsuccessful. If you find yourself second-guessing the point at which you should begin breeding, you should ask your vet for a professional opinion.

There are no benefits in having your dog experience multiple heat cycles throughout her life if you don’t intend on her having puppies. Spaying female dogs is strongly recommended, as it will prevent pet overpopulation on a large scale and will protect them against several health issues that they may otherwise be at high risk of developing. These include mammary tumors and pyometra, an infected uterus that may lead to sepsis, irreversible kidney damage, and even death. Dogs that don’t get a clean bill of health shouldn’t be bred, as the resulting litter may have unhealthy puppies, which leads to deteriorating breed health and welfare issues.
Rhodesian Ridgeback Mother Dog With Puppies
Image Credit: olgagorovenko, Shutterstock

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The 4 Stages of the Canine Reproductive Cycle

During the heat cycle, your dog will go through four stages. If you plan on breeding your dog, you’ll need to understand each one and what it means for breeding. By following these stages, you’ll be able to predict the best times for breeding. This information is also useful if you have a female dog that you want to get fixed. Speak to your vet about the best timing for the procedure depending on the stage of her cycle and how to protect her from an unwanted pregnancy.

1. Proestrus

This is the first stage of the heat cycle, and it lasts for about 9 days. Males become highly attracted to females during this first stage, though most females won’t be receptive at this point. You’ll notice that your dog begins discharging some blood and that the vulva swells; these indicate that proestrus has begun.

2. Estrus

This part of the heat cycle lasts for 3–18 days, depending on the dog. During this time, the female is fertile and receptive to male interaction. This is when she should mate for the best chance of breeding success. You’ll know your dog is in estrus when the discharge decreases and becomes lighter in color.

beagle on estrus cycle
Image By: Sigma_S, Shutterstock

3. Diestrus

Diestrus follows after estrus and usually lasts around 60 days but can be anywhere from 10 to 14 days after heat. During diestrus, the discharge from your dog has disappeared completely. The vulva has returned to normal size, and the female will not permit any further mating. Once all signs of discharge and swelling have abated, your dog is no longer in heat.

During this stage, dogs that have been successfully mated may be pregnant or may experience a false pregnancy. Get your dog checked out by a vet for pregnancy diagnosis and planning or to treat pseudopregnancy if she is not acting like herself and has started producing milk.

4. Anestrus

Anestrus is the fourth and final stage of the reproductive cycle for dogs. This is when there is minimal ovarian activity. It lasts a minimum of 7 weeks, but for most dogs, it lasts 18–20 weeks.

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Final Thoughts

During heat, your dog is going through a lot of hormonal changes, and you have to contend with extra mess and sometimes erratic behavior. Luckily, canine heat doesn’t last long. For most dogs, it lasts just 2–4 weeks, so you’ve got less than a month of dealing with all the headache that accompanies the heat cycle. Then you’ve got 6 months off until you have to deal with it all again!

If you’re not planning on breeding your dog, speak to your vet about the benefits of getting her fixed, as it will prevent her from developing serious health issues in the future.


Featured Image Credit: atiger, Shutterstock

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