The dog heat cycle (estrus cycle)

Please share us!

For several different reasons some owners may not want their female dogs to get spayed. For the owner of such an “intact” female some knowledge about the heat cycle is helpful to prevent “accidents”. In this post you will find information on the heat cycle in dogs, signs to look out for and measures to take.

In this relating article I am introducing a neat way to keep the bloody messes under control during your dog’s heat – with the dog heat suit

The dog heat cycle (estrus cycle)

First and foremost it is important to note, that dogs are very different and that there is NO rule of thumb valid for EVERY dog, when it comes to heat cycles, especially regarding length and signs.
As pet owners our best bet is to rely on our personal perception of our dogs and changes in their moods or bodies – rather than just looking for discharge etc.

Steve Gogulski, breeder and owner of assisted me with answering some interesting questions to be found in this essay, offering more detailed insight into the heat cycle in dogs from a professional perspective.

www.bullterrierfun.comBTF: “Steve, one of the most common questions owners have is probably “How often will my female come into heat?”. Are there any statistic numbers?”



bullterriersofnc.comSteve Gogulski: “The problem with answering this question is the fact that no two females are the same and heat cycles can change depending on age, whether they are being bred, other females they are around which come into heat, health, activity level, etc.”



The main and important period of a heat cycle in dogs lasts about three weeks. During this time the dog undergoes three different stages, followed by a fourth “resting” stage:

Stage 1 – Proestrus

Proestrus is a non-fertile stage. Bleeding may or may not occur depending on the individual dog. Some dogs experience almost “silent’ heats, while others do bleed a lot. The proestrus usually lasts about nine days* (but that can vary!).
This stage is marked by an increase in the female’s estrogen level (can only be accurately determined by testing). The dog is not receptive to males yet, but from now forward she will more or less obviously show many of the signs of heat. Possible signs are moody days, swollen teats and/ or vulva and/or having to “go” more often. Females in heat naturally understand that marking their scent during urination in several areas outside will attract males that will easily and instinctively pick up the scent of a female in heat thus the desire for them to use the bathroom outside more often.
In many dogs it is hard to rely on the occurrence of bloody discharges alone, as they may differ a lot!
But every owner who knows their dog’s behavior quite well will notice other mentioned changes (explained in more detail below).

Another significant sign are males becoming more interested in your female.
If you notice males becoming interested or your female is showing the signs of entering her heat , you should avoid all contact (not only mounting, but also the dogs’ rears touching etc.) between your female dog and males. The reason is that mounting is not mandatory to introduce semen in the right places and that semen can survive for about a week under the right circumstances. If your female catches semen while non-fertile, but then becomes fertile while the semen is still alive, chances are she could still become impregnated. Females have become pregnant while being completely separated in a kennel run from males. Even with a kennel or chain link fence separating a male and female, conception can occur. This is often when you hear about an owner explaining that they think a neighbor’s dog jumped over their fence and bred to their female which resulted in pregnancy. Rarely those are owners aware of the fact that leaving their female to roam free in their fenced in yard has probably attracted every intact male on the block, which are said to have the ability to pick up the scent of a female in heat for up 3 miles and may have resulted in a pregnancy through the fence.

Read on about Phase 2, the Estrus, on the next page.

35 thoughts on “The dog heat cycle (estrus cycle)

  1. Hi
    My puppy Arna come into her first session on the 24th September 2016 and has only stopped bleed for 4 days since then, she humps her bed so I take it away from her, she seems fine in herself, but a few weeks ago she got a bad tummy upset and had to stay at vets, for the day, she now growls in her sleep and in the evenings, she is very friendly with other dogs she meets and people, I have had several tests done on her and nothing shows as being wrong, she is deaf in one ear so I was going to get her spad. Has anyone else had this problem with there bitch

    • Hello Sonja,
      I am afraid, I can’t really figure out the core problem you are seeking answers for. You seem to be dealing with different issues. Which one is the problem you are trying to resolve? Is it the humping or the growling or the question, if having her fixed would be a good idea or not?
      Once I know what exactly is bothering you, I will be happy to provide advice.

  2. Hi I have a female bull terrier that will be one year old in February she started bleeding and has been bleeding for over a week I was wondering how long do they bleed, i feel bad since i have her in her crate all day other than letting her out to use the bathroom or somedays outside her kennel.

    • Hello Jenn,
      in my experience heat cycles are really different with every single bitch and the bleeding can last up to three weeks.
      During that time you should remove valuable floor coverings, if possible and use towels and blankets to cover places the dog is using (sofa etc.). Also you can limit the dog’s access to certain areas. But it is never a good idea to crate this breed – or actually any dog – for longer periods of time, just because they are messy. Bull Terriers easily get bored and tend to develop obsessive and self-destructive disorders, when crated or kept on short leash without entertainment for longer periods of time (that can even be just a few hours). And that can lead to a whole bouquet of other problems that are much harder to deal with than just a few blood stains.

      There is a very good cleaner available – I am using it all the time – they have different varieties for different problems:
      Nature’s Miracle Stain & Odor Remover
      It does not only remove stains, but also neutralizes odors. That stuff works wonders!

      To reduce messes when my girl is in a heat cycle, I am putting her in a suit. I wrote an entire essay about it, because I am thrilled by this product, you’ll find it here:

      The Suitical Recovery Suit for Dogs was originally invented for dogs after surgery.

      But it really does a great job during a heat cycle also! I can even let my dog sleep with us in bed, because it works like a romper on a toddler – no messes!
      I hope this info helps. Please feel free to ask more questions anytime.


  3. My female was in heat in december 2016,her heats r 7 months apart. Shouldn’t she be in heat now?on july 11 she had a few drops tgat lasted about 3 days..i was hoping to breed her again this cycle..she is a siberian husky

    • Hello Dianna
      Usually, I am more than happy to provide advice. But in this situation, I think a vet visit or a test kit is well warranted. Because the best way to find out what is going on is to have an ovulation test performed on the dog, especially if you intend to breed her. Dog’s cycles can vary and even be completely irregular. If you have read the essay you’ve commented on, you already know that blood is not a very reliable indicator for the dog being in its fertile phase.
      A vet can also test for other breed specific issues and tell you if your dog does bring the right genetic conditions for breeding.

    • Romano,
      if you referring to your dog’s vulva noticeable swelling is quite possible and normal. If it’s only swelling and she does not seem to feel uneasy or sick in any way, I would probably not be worried.
      Her teats could also be swollen already, but usually this happens a few months later, about the time when the dog would be wet-nursing her offspring. That is usually the time when the teats grow larger in some bitches – pregnant or not. A few weeks after the heat a false pregnancy could occur as well and contribute to even more swelling. Even a little lactation can happen. Going back to normal for the teats could take a while. With my girl it always takes months.
      If there’s anything you really worry about, buy yourself some peace of mind and let a vet take a look at it. He will also be able to give you some expert advice.

  4. Hi I have a bull terrier cross staffy she is 6 months and I want to get her desexed before her first cycle. I know they say that they can get their first cycle from 6 months on but I’m just wondering if you have a rough idea of when that might be. Thanks

    • Hi Michelle,
      I really think this is the perfect topic to discuss with your vet during the next routine exam or so. I am not able to give advice from a medical perspective, simply due to lack of experience. I am actually strongly opposed to spaying/neutering. My girl is 4 years old now and still intact. During my life with dogs I had to deal with the issue only once when my last Bull Terrier was suffering from a life threatening infection and the only way to save her life was to surgically remove her entire womb.

      I will not try and talk you out of your plan because I believe that everyone has to make their own decisions based on conviction and circumstances in life.
      Yet, just in case you are interested to know more about why I do not favor fixing dogs here’s an interesting video that explains some of the reasons:


  5. I have a pure bred bull terrier. AKC regiestered pet. She is 8 months old. She is exhibiting some very unusual behavior. She is highly intelligent. The vet told me that her purebred DNA could be of concern. He said she could flip out on me and get very dangerous. Watching her grow up stong and beautiful has been a real joy. He has green eyes and snow white color. Any fact behind this vets opinion that her DNA will kick in and she becomes dangerous?

    • Well, that story sounds odd on different levels. First of all, if it is indeed an ENGLISH Bull Terrier puppy with AKC pedigree I am wondering about the green eyes. Because for all I know brown is the standard color. Secondly, this is the first time I have heard of a vet predicting aggression based on the dog’s DNA. On the other hand you’ve mentioned “very unusual behavior”. Wondering what that means.
      Sadly, there is by far not enough information in your post – neither about the behavior, nor the fundaments of the vet’s statements – to get a real picture of the situation and say something.
      If you like to provide more details I’d love to look into it again.

      • Definitely not a purebred English bull terrier if Eyes are green, actually a purebred English bull terriers eyes are black. My girl had her first heat at 7 months, now she’s approaching 17 months and still no signs of a second heat. Is this normal?

        • Neither normal nor abnormal. It’s just impossible to tell at this age without an exam. Her body may still be in the process of developing and moving into the repeating regular heat cycles. I think this is an excellent question for your vet at the next routine exam.
          If your dog seems happy and healthy I would not be too worried at this time and wait a little longer. However, if you are worried, I recommend a vet visit.

  6. Hi, I am wondering after a female heat cycle, to know when the next cycle should begin, should I count from the beginning off her last cycle, or the end? Thanks

    • I can only tell you how I am doing it: I am tracking the time-frame during which I notice bleeding in my girl. I know that this is likely not the entire period of her heat, because I always notice her being swollen around her private parts quite a while before the bleeding starts. The swelling is my warning sign that she is due. So, I basically know before the bleeding starts that the time has come and can take precautions. I keep track in a calendar and meanwhile I know that my girl is getting into heat pretty accurately about every nine months. From past experience I also know that her bleeding will last for about three weeks.
      While the swelling is a pretty good indicator already, the bleeding is something I can definitely pinpoint with start and end and count the days. So, that’s my orientation. As a result of my own experience I am starting to count the next nine months after her last heat from the LAST day I notice bleeding. That works good for us.

      If you are trying to identify when she is in her morst fertile state during the heat, that is an entirely different story, however. Because as you may have read in my article the bleeding is not necessarily an indicator for a fertile or non-fertile state and the most fertile time can be even BEFORE OR AFTER any bleeding occurs.
      If you want to avoid a female getting impregnated – as I do – there should definitely be an eye on more than just bleeding, such as swollen intimate area, mood changes and such things in order to not miss the point.

  7. Hi, I would like to ask if a dog will get pregnant in her late estrous cycle? I brought her to the vet last time and did a smear test, that’s when I learned that she was on her late estrous stage already. I wasn’t able to track the start of her cycle since I was waiting for a bloody discharge, but I wasn’t able to track a bloody discharge. Same goes on her 2nd heat cycle the difference was on the 2nd heat i bred her on her late pre-estrus and at the beginning of estrus. I was only able to know that she was on heat because of my male dog licking her private parts and trying to mount her. She is a 24mos old siberian husky.

    • Hello Peter,
      recognizing when the dog gets into heat for the average owner is a matter of finding out patterns (how many months apart does the dog usually come into heat) and getting to know their own dog and interpreting the signs.
      Other than that only LOTS of experience and specific tests (there are test kits available that breeders use) can help to determine time and length of a dog’s estrus cycle more accurately. Every dog is different. But according to my experience as your dog ages you will be more and more able to tell just from her behavior and tiny changes on her body during that period. I you don’t want your dog to become pregnant just give it some good extra time before and after you notice signs when it comes to playing with other non-spayed male dogs.

  8. My Staffy ended her heat about 60 days ago but she started to present to the male dogs she is around. The dog we live with continually tries to mount her and wait s for her outside the door and she has no problem with him mounting her and she runs up to him and let’s him do it. I am concerned she could go back on heat with no visible signs because she is around an intact male. Is this true? I am wondering your opinion on what to do as he has inseminated her yesterday and it’s not a pregnancy we want. I will take her and get a prog test. I am not sure what else to do.

    • Hello,
      as stated in my essay I am not an expert on dog pregnancy and heat cycles. My article is intended to share the knowledge I was able to gather as a regular dog owner (I’m not a breeder) on the topic. It is not professional advice for the very reason that I am not a professional.
      Your issues are very specific, which is why I am not able to provide further advice except suggesting to discuss this asap with your vet if you are afraid that your female dog will become pregnant. Sorry that in this case I can’t be of more help.

  9. Hi there
    My staffy girl is 17months and has had 2 heat cycles so far (4months apart) i have spoken to a vet and she doesnt seem to concerned as long as the blood is normal in colour which it is. As shes quiet young our vet and breeder have both said she may regulate to every 6 months as she gets older.
    But can they go every 4months?

    • Hi Meegan,
      my girl seemed a little irregular during her first few heat cycles, too. But over time it really balanced and now I can almost predict to the day when she is becoming due every six months.
      Give it some more time. If after the next two to three cycles she is still on four months, I would talk to the vet again just to be sure this is nothing to worry about.

  10. My girl, is 10 months old 39 days since possible breeding. Her teats and vulva are still swollen. Teats glands seem to be going down. Do you think this is possibly a false pregnancy or real?

    • Hi Genia,
      In my experience, the teats often start swelling even more AFTER the heat cycle is finished and they can stay enlarged for a long time (weeks to months). This happens due to the hormonal situation in the dog’s body with or without a present pregnancy.
      Enlarged teats are not a reliable indicator of present or absent pregnancy. If you are not sure if your dog is pregnant, only a pregnancy test can give you a reliable answer. Also the teats are no indicator of a false pregnancy. A very reliable indicator is the dog starting to carry around small toys like they were puppies, whimpering and emotional behavior.

  11. My female has been in heat four weeks and a one day. Visually there are no signs that she even should be, but my female is still VERY MUCH trying to breed her. Can anyone help us? Should be bathe her to remove any residual smells? What’s the longest anyone knows of a cycle?

    • All I can tell you is that “visual signs” are no reliable indicator of anything. If you have an intact male and female in the same household and the male keeps trying to mount her while you don’t want your female to become pregnant you should keep them completely apart until you are absolutely sure that your female’s cycle is over (either by giving it enough time or talking to your vet to make sure).
      Washing will not change anything. You can’t wash away hormones and other signals the body is sending when a female is ready to mate.

  12. Hi was wondering if you could help me my girl just turned a year on the 18th of March she started her season on the 10th of March she was really swollen then she started bleeding a few days after now that’s 4 weeks up and she’s still really swollen , really red and bleeding again , she won’t stop licking herself constantly she can’t sit still without licking am worried about her could you help ?

    • Hi Nicole,
      sorry for the wait. I was so busy during the last weeks that I did not get the chance to take a look into the comments.
      The heat cycle can vary a lot in appearance, lengths and intervals inbetween.
      There is no golden rule here.
      Often the first one or two cycles also go a little different, like the dog is adjusting. Over time, the mentioned factors, such as appearance, lengths and intervals inbetween should kind of balance and the dog should become regular.
      If that is not the case or if one cycle does develop significantly different from the last ones – which of course you can only know if your dog already went through some cycles over time – than it is time to have the dog checked by a vet.
      I hope that your case has resolved in the meantime and that your dog is well and healthy!

    • Hey Mark, at this point I would not be overly concerned and just give it a little more time as long as your sweety seems to be happy and healthy. The heat cycle is a highly individual process in every female dog. Some hit their first time sooner, some later. If I remember it correctly, Mila hit her first one at the age of 9 months.
      Maybe talk to the breeder if you get a chance, see if he/she has any helpful info or advice.
      And of course, if you suspect anything to be wrong healthwise I’d recommend arranging a vet visit.

  13. My bitch has been out of season for about a week but I also have a male this was her first season since she’s come out it her nipples have gone big and teets swelled abit should I be worried she’s 8months old xl bully

    • Hello Jake, I am not quite sure what your exact concern is. Are you afraid that your dogs may have secretly hooked up and your girl may now be pregnant? Or are you worried that the swollen teats may indicate some kind of health issue?
      I have no experience with pregnant dogs. I was too young when my parents had a litter ages ago.
      All I know is that my girl (she is still intact) gets a swollen vulva during her heat, which is normal. And she gets swollen teats about 6 weeks AFTER being in heat, which is also normal, because in intact dogs the body often exercises the entire pregnancy thing through, no matter if real or not. If the dog is not actually pregnant this is called a false pregnancy. I have never heard of or experienced a noticeable enlargement of the teats during or RIGHT after the heat, however.
      So, if there is a really obvious teat swelling occurring right after the heat, would that make me nervous? Yes, it probably would and I would talk to my vet about it just to make sure.
      That’s all I can say. Hope it helps.

  14. I have a female bull terrier that turned 8 months on Christmas Eve. Her vulva is swollen and has been spotting since Wednesday. Everything else about her is normal. Could this be her first period?

    • Sounds pretty much like it could be the first heat to me. But that is nothing more than a guess because I can’t make a diagnosis (not a doctor, did not even see the dog). Please be aware that if it’s the heat seeing blood or discharge does not mean that your dog is or is not currently fertile. If you want to avoid accidental impregnation you may want to avoid contact with other intact male dogs for a few weeks.
      If you suspect anything else as the reason behind the described symptoms or are concerned in general about the health of your dog, I recommend to see a vet with her.

  15. Hi all,
    I have a 20 month old beautiful EBT. She had her first (short) heat at 7 months.. She had her full heat in August this year 2022..
    Its only October now and this last week she has displayed behaviour like nesting, crying nearly constantly and extremely boisterous stuff when out walking… Im wondering if she may be approaching another heat? Her vulva isn’t swollen (yet?) and shes gone of certain foods aswell..Ive read different things but was hoping someone may be able to shed a bit of light through experience…
    Thank you for reading
    Jennifer 🐾ebt🐾

Leave a Reply

Your email address will not be published.