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A female dog in heat presents her owners with some challenges, especially if this is her first heat. Both the animal itself and her owners must eventually learn to cope with sexual maturity. This article will tell you how long a dog's period - technically called oestrus - lasts, how the behaviour of female dogs (as well as any male dogs in their environment) changes depending on the phase of the cycle, and what you should do when your dog "gets her period".  
Most female dogs come into heat for the first time between their sixth and twelfth month of life. However, some female dogs take a little longer and don't come into heat until they are two years old. When a female dog becomes sexually mature depends on her size, her physical development and her general condition. Large and malnourished female dogs, or those that have been ill, tend to come into heat later than smaller and completely healthy dogs. Adult body weight is decisive for sexual maturity. An unspayed female dog will experience heat throughout her whole life. The absence of heat can be a sign of disease, even in older animals. 


There is no such thing as menopause in dogs. A dog's periods will become less frequent and the symptoms will become less pronounced. But female dogs can fall pregnant throughout their whole life. 

A female dog's first heat is often slightly atypical, as the animal has only just become sexually mature: in the middle of puberty, the body is not yet fully developed, which can lead to a silent heat - also called white heat. In this case, the typical hormonal processes will not cause any external signs, such as bleeding or swelling. The female dog may therefore come into heat "silently" - and become receptive. In other cases, clinical signs of heat appear at first, but they suddenly stop a short time later, only to reappear a few days later. Vets call this cycle disorder split heat or split oestrus. Neither silent nor split oestrus is pathological. 

Good to know!

Dogs of the primitive type - for example the Basenji, the Dingo or the Thai Ridgeback - as well as the Nordic dog breeds often only come into heat once a year.  

If your female dog does not come into heat after her first birthday, it is not necessarily due to illness. Some animals simply take a little longer, especially if they are bigger, come from a bad stock, or were ill when they were young. Some animals have a normal cycle, but without the typical symptoms (see silent heat). You should still consult a vet as a precaution to rule out a health problem. There are many possible causes for a female dog failing to come into heat. The most common include:

  • Ovarian dysfunction
  • Hypothyroidism
  • Adrenal hyperfunction
  • Congenital chromosomal disorder


If your female dog's heat lasts for a long time or is very short, you should see a vet. This is the case if either the bloody discharge or the readiness to mate last more than three weeks or if the proestrus and oestrus phases together last less than ten days. 

The duration and sequence of the heat are very individual and vary depending on the dog. Regardless of the time component, however, a female dog's cycle of heat includes four phases:

Pro-oestrus: 3 - 17 days

During pro-oestrus, a female dog's vagina swells and bleeding occurs. The female dog will begin to smell good to male dogs, but is not yet ready to mate. Many begin to mark at short intervals along their walking route - similar to the males. This is how they inform potential mating companions of their readiness to mate. 

Oestrus: 3 - 21 days

The swelling of the vulva subsides and the discharge becomes watery or slimy instead of bloody and yellowish. At the beginning of oestrus, usually on the second, third or fourth day, there are several inroads. The fertile period is called standing heat: during this phase, the female dog is ready to mate. 

Post-ovulation (metoestrus): 9 - 12 weeks 

The vagina is completely swollen, the discharge disappears. The female dog will still smell appealing to inexperienced males, but their interest will continue to drop. She is usually no longer ready to mate. As the progesterone level remains elevated for about 59 to 62 days after ovulation, regardless of whether the female dog is pregnant or not, many dogs experience pregnancy after heat. 

Dormant phase (anaestrus): several weeks or months

The dormant phase is highly individual and can last for different lengths of time. The female dog will show no signs of being in heat. The dormant phase ends with the initiation of pro-oestrus. 

Although a dog's sexual cycle can be precisely described, it differs in every animal. The transitions between the individual phases can be smooth and difficult to recognise, which may mean that you will not be aware when your female dog is ready to mate. Some female dogs will show little or no behavioural changes, while others will respond noticeably. Some female dogs experience their heat very intensely and also suffer from false pregnancy every time. Some will forget their training and are difficult or impossible to call back. Some are more affectionate and want to cuddle more than usual, and may seem sluggish, melancholic or lazy. Others will become over-excited and won't settle down. You will need to observe your dog carefully to spot symptoms that are barely noticeable. 


Do not rely on the clear divisions of fertile days - biology has a very elastic nature.  

In the pro-oestrus phase, a female dog won't want anything to do with her animal fan club. She will avoid male suitors or try to chase them away by snapping. During their first heat, female dogs are often very insecure and feel harassed by pushy males. Some react fearfully and try to flee, while others "freeze", remaining motionless and enduring other dogs around them. Others will try to distract their suitors' attention and attempt to play with them. 


Only walk your dog on a lead during this time and choose walking routes that are not as heavily frequented by other dog owners. Ask other dog owners to leash their dogs too. If you encounter dogs off their lead, stand in front of your dog protectively as a precaution.  

During the crucial oestrus phase, a female dog will become interested in her admirers. She will often willingly stand still and turn her tail to the side. Most female dogs actively try to make contact with males during this time - even the most obedient ones will sometimes switch off and run away to ensure the reproduction of their species. 


Use quiet routes or walk your dog at times of the day when fewer other dogs are out and about. The lead is an absolute must - not only to avoid an unwanted pregnancy, but also to protect your female dog from any accidents. When in heat, the senses are somewhat "dulled" and a female dog may run in front of a car as she searches for an admirer.  

During the two to three months of metoestrus, a female dog usually loses all interest in mating and devotes herself to her - real or imaginary - pregnancy. As the progesterone level remains elevated for about two months after ovulation, a female dog may have a psuedo-pregnancy. Depending on the interaction of hormones, a female dog may have a more or less pronounced false pregnancy. Some animals produce a lot of milk and their teats swell; others become even more affectionate than usual; some have a bigger appetite; and others start building nests. Many carry cuddly toys around and lick them. Some female dogs are so badly affected by this that they seem traumatised when the offspring fail to arrive.


If your female dog is unwell during this time as the false pregnancy causes significant suffering, contact a vet or veterinary practitioner.  

In the anaestrus phase, the female dog will be "back to her old self" and will no longer show any behavioural abnormalities. She will react normally to her environment again: playful dogs will wish to play once again, shy dogs will be reserved once more, and uptight dogs will be fussy again.  

  • increased marking
  • increased following of local males
  • swollen vagina
  • barking or snapping at pushy males
  • unwillingness to return when called back
  • great attachment and cuddliness
  • sluggishness or restlessness
  • bleeding
  • increased licking of genitals
  • yellowish, watery or mucous discharge
  • tail turned to the side

If female dogs in the neighbourhood are in heat, unneutered male dogs will display the following behaviours:

  • restlessness
  • barking, whining, yelping
  • loss of appetite
  • pulling on their lead
  • partial or complete unwillingness to return when called back

In addition to all the mental and organisational challenges that owners of unspayed female dogs face, there are also some pragmatic aspects: how should you deal with a female dog's bleeding, especially around high-quality furniture or in a car with a well-cared for interior? Although most animals clean themselves often and extensively, you can protect your furniture and car upholstery with blankets and put protective pants on your female dog, especially if she bleeds heavily or neglects her hygiene at times. Hygiene pants will prevent any discharge from ending up on the carpet, sofa, or dog bed. Ideally, you should get your female dog used to these pants in good time - otherwise she may wriggle out of the unwelcome "underwear" quite quickly. 


Hygiene pants do not protect against mating and pregnancy! 

Despite all precautions, sometimes accidents happen. If your dog has escaped, but you want to avoid unwanted offspring, you should act quickly. Unfortunately, there is no pregnancy test for dogs that you can use at home. However, a vet can take a vaginal swab to determine which phase of the cycle your female dog is in and whether pregnancy is likely. As a precaution, you can also have an ultrasound examination after three weeks. 

If your female dog has become pregnant unintentionally, there are a few ways to terminate the pregnancy:

  • Spaying
Possible up to the 40th day of pregnancy, but as early as possible for ethical reasons. During the operation, the foetuses are also removed. After the 40th day of pregnancy, complications often arise because the tissue of the uterus is very heavily supplied with blood and bleeding from the ovaries can occur.  
  • Treatment with oestrogens
Possible up to three days after the unwanted mating. The risks here are life-threatening pyometra (suppuration of the uterus) and hormone-induced bone marrow damage. 
  • Abortion injection with prostaglandins 
An injection between the 30th and 35th day of pregnancy leads to the rejection of the foetus. 
  • Administration of gestagen inhibitors
Administered between days 25 and 45, this is probably the safest method of abortion in dogs. Gestagen inhibitors block the body's own nerve receptors that maintain pregnancy, resulting in termination of pregnancy within one to eight days.

Modern medicine makes it possible: hormonal suppression of heat is also available for dogs - not in the form of tablets, but injections. Many vets advise against this, however, because - as with any hormonal manipulation - it can lead to suppuration of the uterus (pyometra) and mammary tumours. It can also promote diabetes. If hormone injections against heat cannot be avoided - for example, because you also have an unneutered male dog at home - they may only be injected during the dormant phase and never during heat, as otherwise the uterine mucosa is damaged. They should also not be used as a long-term solution.  


Over time, the interval between heat cycles and their duration will become regular. Make a note of when your female dog comes into heat, indicating the first bleeding, standing heat, and the end of heat. This will make it easier for you to plan your holidays or visits to pet owners with an unneutered male dog.  

A female dog usually comes into heat twice a year and goes through behavioural changes (which can be severe) during that time. Many pet owners experience "heat" as a stressful phase that includes running the gauntlet during every walk and unsightly protective blankets in the house and car. If the accompanying symptoms (such as a traumatising pregnancy or particularly severe psychosomatic reactions in the female dog) are limited, definitive interventions such as castration or hormone injections should be avoided. With the necessary knowledge and a few practical tips, you can get through your dog's period well. After all, it is a natural process.