Menstrual Cycle in Dogs | Petlebi

Dog Health

Menstruation is a process seen in humans and primates. Every month in humans, women’s uteruses prepare for pregnancy. When pregnancy does not occur, soft tissue and blood are expelled from the body. This process takes place, on average, once every 28 days. Female dogs entering adulthood go through a similar process. However, this process is very different from that in humans or primates. “Do female dogs menstruate?” The answer to the question is yes, but this process is more complex. In female dogs, the cycle continues with different durations and phases. The cycle in dogs is called the estrous cycle. When this cycle begins in dogs, certain behavioral and physical changes occur. Therefore, it is quite easy to notice the estrous cycle. In this article, you can find answers to frequently asked questions about the estrous cycle in dogs.

angry-eyed dog

Cycle Processes in Dogs

In dogs, the estrus cycle occurs instead of the menstrual cycle as in humans. This cycle is divided into four different phases in itself. Each phase lasts for a different length. These stages are divided into four: anestrus, proestrus, estrus and diestrus.


“Do dogs have periods?” The period when the question is asked most frequently is the proestrus period. Because visible changes occur during this period. Many dog ​​owners also refer to this period as the estrus period. The proestrus period lasts an average of 9 days. However, the process can vary between 0 – 27 days. The proestrus period is also the period when male dogs are attracted to female dogs. However, females do not accept male dogs and even behave aggressively towards them. During this period, estrogen is at its highest level and follicles begin to develop. The vulva begins to swell and bloody discharge occurs. In the proestrus period, an increase in the appetite of dogs is observed. Also, their personalities change. Female dogs have more irritable behaviors during this period. It also releases hormones and pheromones to show male dogs that it is ready to mate. For this reason, they urinate more frequently. Vaginal cytology performed during this period reveals different types of cells, most of which are red blood cells.


This is the period when female dogs now accept male dogs. Considering the behaviors, it can be said that it takes an average of 9 days. However, estrus can be a process ranging from 4 to 24 days. During estrus, the female dog is ready to breed. The vulva enlarges and softens. Bloody discharge is greatly reduced or completely eliminated. During this period, estrogen levels decrease and progesterone levels increase. During estrus, female dogs usually bend in front of their front paws, raise their tails and shake them from side to side. In this way, they try to attract the attention of men. Epithelial cells are usually seen in vaginal cytology. Dog breeds enter estrus twice a year on average. While this period decreases to once every four months in small breed dogs, it can go up to once every two years in large and giant breeds.


The estrus phase is followed by the diestrus period. During this period, females lose interest in male dogs. Diestrus period lasts approximately 2 months. Estrogen levels are low. Progesterone peaks 3 to 4 weeks after the onset of diestrus. In the next process, it starts to decrease towards basal levels. This change in progesterone is not due to pregnancy. So even if the dog is not pregnant, the progesterone level rises. For this reason, foreign pregnancy occurs in non-pregnant dogs. After false pregnancy, dogs’ appetite increases and weight gain occurs. Cytology shows a return to basal cells and the number of red blood cells is less than in proestrus.


The period between diestrus and the next proestrus phase is called anestrus. Although this period varies according to the species, it lasts approximately 5 months. The vulva is of normal size and there is no vaginal discharge. During this period, the body prepares the uterus for the next pregnancy. In cytology, only basal cells are included.

female dog stretching with her puppies

When Is the First Cycle in Dogs?

“Do female dogs have periods?” The question that should be asked instead of the question should be when the dogs menstruate. Because, as in all mammals, it is normal for dogs to have menstrual cycles, but the start time of the cycle varies according to dog species. Small dogs may experience their first estrous cycle when they are around four months old. In large or giant breeds, this process can take up to 18-24 months. However, on average, the first heat is seen at the age of 6 months. Although dogs have the biological competence to become pregnant during this period, their eggs have not reached sufficient maturity. For this reason, it should be waited until the end of the second estrus cycle at least in order for the dogs to be mated to have a healthy pregnancy process. The time between cycles increases with age.

dog lying in front of the window

How to Approach Dogs in their Oestrus Cycle?

Significant behavioral changes also occur when dogs enter the estrous cycle. “Do dogs menstruate?” It should not be forgotten that the answer to the question is yes, and how to approach them is extremely important. On average, bleeding occurs in the first two weeks. In this process, precautions can be taken with various pads or cloths. You can find products such as dog diapers and dog panties that dogs can easily use by clicking here. Female dogs become more anxious and irritable with estrus. Some dogs may even experience extreme aggression. In this process, it is necessary to be careful when approaching the dog. Those who want to mate their dog should be careful against accidental mating. In the meantime, since female dogs attract the attention of male dogs, it is important to limit interaction with male dogs in order to prevent pregnancy. Since there may be various genetic problems in the puppies of dogs from different breeds accidentally mating, it is necessary to be sensitive about this issue.

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