How Long Does a Dog Stay in Heat?

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How long does a dog stay in heat? Once a dog reaches its puberty, it has its first estrus cycle. This stage is the reproductive cycle that may result in dog’s pregnancy. A dog in estrus is said to be in heat or having its “season”. At about six months of age, a dog reaches the puberty, some breeds reach it later. Small breeds have their first estrus cycle or heat at earlier age, while bigger breeds should reach at least eighteen months or even two years of age.

Although the heat length varies with different dog breeds, the whole cycle lasts for 2-3 weeks only.

Swelling external vulva characterizes the onset of estrus. The heat ends when the vaginal discharge disappears and the vulva returns to normal size. Therefore, the answer to the question is simple: 2-3 weeks. However, the whole topic is subject to a big deal of science definitions and processes that deserve more information. This is why we are going to develop the topic to cover everything that is connected with the dog heat so that you, the owner, can learn to know more about your dog.

Signs of a Dog in Heat

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You know you wanna

Prevention of unwanted pregnancy is one of the problems that all dog owners face from time to time. The responsibility to prevent unwanted pregnancy lies with owners of dogs. However, the majority of the work lies on female dog owners.

In order to prevent unwanted pregnancy, every female dog owner should know when the dog can become pregnant. Every dam/bitch/female dog (synonyms) may get pregnant during her estrus, otherwise known as the heat cycle. Dogs do not have menopause that all humans have. Growing older, a dog can still get pregnant, even though her fertility is low compared to the previous young years. Typically, a dog has two heats every year. If you breed dogs on purpose or are a commercial breeder, you should know that breeding starts once the dog passes her third heat.

The heat cycle comprises four stages: proestrus, estrus, diestrus and anestrus. Proestrus is the preparation stage that doesn’t make the dog fertile. You should know that sperm lives several days and you should take precautions against unwanted mating. To do so, consider getting special pants to protect your dog from unwanted suitors. It is important to know when the dog is coming into heat and going out of it. There are signs and clues that will help you to learn about her behavior.


This stage lasts 4-20 days. This stage shows three signs for a dog in heat:

  • Swollen vulva. The swelling takes place also in teats, but this is not the best heat indicator and can be hard to spot.
  • Discharge. This is very common with all dogs. You may notice that the dog spends a lot of time licking herself. Once you notice swelling in the rear, wait for the discharge to appear. It will tell exactly that the dog is coming into heat. Should you notice the bloody discharge, you may begin the countdown.
  • Suitors. It is the third sign. Presence of male dogs around means that they can smell the female dog being in heat and she is definitely experiencing one. During this stage, you can evade unwanted pregnancy by simply avoiding long walks in the parks or doing it earlier than usual. Also, consider keeping the dog at home during these days (read also


Around day 24 begins this stage. It lasts 60-90 days and the dog is no longer fertile. The discharge changes its color from straw to red and then ceases completely. However, the dog still reeks the heat scent and may still attract unwanted attention. Before returning to public places and for usual walks, wait until the dog has stopped bleeding.


This is the final stage of the heat cycle. At this stage, the dog returns to “normal” mood and behavior. This stage lasts 60-90 days by the end of which the second year heat cycle starts.

Dog in heat
Oooh, really?

Heat Cycle Abnormalities

The stages of heat cycle described above reflect the statistic norm. However, the heat cycle may be abnormal. In this comprehensive passage, we are about to describe the anomalies that heat may show. Young female dogs often have silent or irregular heat periods, which do not present any serious hazard unless you are a breeder, aiming at high-grade litter.

Silent Heat

Silent heat means that the signs of the cycle go almost or completely unnoticed. Such heat cycle escapes detection because of little bleeding and minimal swelling. A dog experiencing silent heat may show no interest towards studs, except for a short period of ovulation. Small dogs usually reach maturity earlier than bigger dogs and therefore, may undergo one or even two silent heats before showing an obvious cycle. If the heat goes unnoticed, the dog may be diagnosed as the one with absent heat. The bleeding goes unnoticed because the dog licks herself much and less discharge means that there is almost nothing to spot. However, a mild vulva enlargement still occurs, though not visible from distance. Also, the swelling of proestrus is likely to happen, no matter what kind of heat the dog is experiencing. If it is vital for you to know exactly whether the dog is in heat or not, you may ask the vet to perform vaginal cytologic and progesterone tests which are two most accurate methods.

Split Heat

This abnormality provokes the splitting of one heat into two separate cycles. Actually, it is happening exactly as it is described, but the picture is very similar. In the first small cycle, the dog attracts the male and shows swelling and bleeding typical for proestrus. The dog does not proceed to estrus and goes out of the heat without being receptive. Several weeks later, the second heat takes place which proceeds to standing heat. The young dogs are more prone to the split heat which is caused by the lack of pituitary output of luteinizing hormone. Because this hormone level remains intact, the ovaries do not release follicles and the progesterone serum remains low. The next cycle is normal and no treatment in majority of cases is needed.

Dog bitch in season
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Prolonged Heat

Such anomaly happens when a female dog remains in heat more than 21 days. During the prolonged heat, the dog displays vaginal bleeding and remains attractive to studs. Prolonged heat, as well as the split is rather normal for young bitches going through the heat for the first time. Later the cycle normalizes.

The prolonged heat may also be the result of persistent high level of estrogen provoked by an ovarian cyst or by a granulosa cell tumor of the ovary. In order to confirm the diagnosis, you should visit vet and ask him to perform tests on vaginal cytology and serum estrogen. Ultrasonography may also be helpful: it shows possible consolidation in tissues (ovarian tumor or cyst in this case). Ovarian cysts tend to regress but if they do not, surgery may be required (see Tumors must be removed surgically at once . Prolonged heat must be treated as it is rather abnormal and the dog’s body experiencing hormonal imbalance. Vets prescribe androgens for long-term use (3-4 months). Androgens otherwise known as male hormones, suppress the estrogen output so that the bitch responding to the androgen application begins new proper heat cycle 4-5 months later.

If the breeding is not desired, you may spay your dog which proved to be very helpful to dog’s health, in general.

Absent Heat

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Catch me!

Absent heat also can be called the “cycle failure”. Females younger than 2 years may have no cycle as they are not mature yet. Large dogs experience no heat until they are 2 years old. If the dog doesn’t experience heat once reaching the age of 2 years, it is a sign to take her to the vet for examination. If the dog has been spayed, the heat will never occur.

Dogs that have undergone operations, experienced severe traumas or malnutrition, do not have cycle until they feel better and restore their overall health. Another common cause of absent heat is the hypothyroidism. The veterinarian must perform a thyroid blood test to establish the real cause.

Ovarian hypoplasia prevents ovaries from developing and thus from producing adequate volume of estrogen vital for normal cycle. Due to hypoplasia, the vulva and mammary glands remain underdeveloped. The cause of the ovarian hypoplasia is the chromosome abnormality. Other reasons also include an immune-mediated ovary inflammation and ovary tumors.

In order to confirm the absent heat, the weekly progesterone and vaginal cytology must be performed. Elevated luteinizing hormone level is present in dogs with the ovarian hypoplasia. Ultrasonography may show the tumor of ovaries or an immature uterus. Dogs that show no cycling after six months of study must undergo karyotyping. If the dog has not had her cycle by 30 months of age while the chromosomes are normal, the ovulation can be induced artificially by injecting follicle-stimulating hormone and chorionic gonadotropin. A dog experiencing such grave issues with her fertility is not subject to breeding as she may transfer her conditions genetically to the breed.

Interestous Interval

This interval represents the time between two cycles. Normally, it takes 5-9 months before next cycle begins, but the interval can be longer or shorter. An abnormal interestous interval is the one either shorter than 4 months or longer than 1 year. However, thinking about the interestous interval as of the main reason why your dog doesn’t have her cycle is wrong. Some dogs genetically come into heat every 4 or 10-12 months! For example, a dog-wolf breed Basenji comes into heat once a year only. Otherwise known as the prolonged anestrus, such abnormality occurs in females who previously had their cycle, but do not come into heat after 16 or more months. A common cause of this condition is the ovarian activity provoked by an ovarian cyst, producing more progesterone than needed. Administration of androgens or progesterone externally may produce the similar effect.

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Come to me, dear

Female dogs with healthy ovaries may restore their natural cycle when being kept in kennel among other cycling females who are exposed to males. If such measure is not working, the dog shows low serum progesterone and there is no evident medical reason for the prolonged anestrus to happen, veterinarians prescribe karyotyping to eliminate the intersex possibility.

Shortened interestous interval is the one that occurs for four months or less. This interval must be distinguished from the split heat. In split heat, the first cycle does not progress beyond proestrus and is incomplete. The lining of the uterus due to a shortened interval has no time to repair itself after the damage caused by progesterone during the previous cycle. Eventually, the dog does not accept the embryo implantation and thus cannot become pregnant. However, a treatment may not be necessary as young dogs develop normal interval when they reach the maturity stage.

Premature Ovarian Failure

At six years of age, the ovarian function begins to decline. When the dog is ten years old, the function ceases completely. It is not a problem as most dogs do not breed beyond 7-8 years of age. In some dogs the ovaries cease to function before the due time – as early as 6 years of age. It leads to permanent anestrus that can be confirmed by extremely high follicle-stimulating hormone and luteinizing hormone levels. Unfortunately, the premature ovary aging cannot be treated (more about

Handling the Heat Situation

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You’re not you in heat

When a dog is coming into heat, the owner is likely to choose one of the two approaches in order to treat the situation. First one is about panicking and not knowing what to do; the second one is about ignoring the fact and treating the dog the usual way. Usual treatment sounds reasonable, but what actually does it incorporate?

Here is the list of hints and tips about how to treat your dog when she is experiencing heat:

  • Never let your dog remain alone in the backyard. You may be surprised by the daredevil feats of agility and resourcefulness that studs perform when feeling a dog in heat nearby. Also, your dog can simply dig under or hop across the fence and get away. Use the leash when planning to go outside – even to the backyard.
  • Off-leash walks are forbidden. Despite many misconceptions, a dog can be walked, provided she is leashed. Even though your dog may be well trained and practice off-leash walking with you, the heat changes the name of the game. Now, she is likely to run away in search of amorous adventures should such opportunity appear. Eventually, instincts are stronger than any obedience training.
  • More attention. What it is supposed to mean is that the dog undergoes mental changes once her heat cycle begins. You should devote a bit more time to your dog: more playing time, brushing, talking to her and so on.
  • Evade training and dog shows. All events involving many dogs should be avoided. It means that even walks in the parks should be planned so to avoid any unwanted contact with other dogs. As for the training – it becomes impractical and pointless to such an extent that the possible boredom gets outweighed by the desire to breed (see also Puppy training).
  • Find the perfect balance between rest and exercise. Dogs show different reactions to heat. Some of them are sluggish and seem tired the whole day, while other becomes too restless. Watch your dog’s behavior and try to choose the right amount of exercise and rest. If the dog is too restless, occupy her with more games and spend more time with her.

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  • Leave toys and chews. If you are going away, you should leave her favorite toys and chews. Dog occupied with chewing has nothing else to think about.
  • Menthol camouflage. This trick is done using some menthol put on the tip of her tail. Such trick masks the scent. There are also commercial products that mask the scent available in pet stores.
  • Doggie pants. Pants are used to prevent your dog from leaving bloody marks all over the house. Pants also mask the odor and prevent males from following your dog while you are walking.
  • Consulting a vet. Heat is not an illness, but consulting a vet may be helpful when an unexpected trouble occurs.
  • Spaying the dog. It is recommended to spay the dog if you do not plan to breed her. Some people say that spaying is not natural, but we reply that, not allowing the dog to mate is also not natural. Spaying improves the overall health and changes behavior from partially excited to constantly calm.

How long does a female dog stay in heat? It depends on the breed, the size, natural reasons and possible health conditions. We hope that this article will help you to understand the mechanism of the heat that your dog experiences and how to cope with it.

See also How long are dogs pregnant.