The Dog's Heat Cycle Explained

A pie chart example of the dog's heat cycle

A dog's heat cycle may appear to be something quite difficult to understand. Unlike other species, the heat cycle of canines does not seem to follow any logic such as following a specific seasonality or temperature change. Rather, it just occurs regardless if it is the dead of the winter of the dog days of summer.

Many times the dog's heat cycle, better known as estrous cycle, seems to be quite unpredictable. The first heat generally occurs around six months in small, medium dogs and around 12-18 months in larger breed dogs. However, It is not unheard of some giant dog breeds going into heat at around 30 months of age.

Phases of the Dog's Heat Cycle

The cycle is divided in four distinct phases.

  • Proestrus

This is when the dog's reproductive tissues swell and appear puffy. A bloody discharge will take place as the female carefully licks herself quite often in order to keep herself clean. Loss of appetite and irritability are not very uncommon. Male dogs may be interested in the female but she will not be interested as of yet. This phase generally lasts seven to ten days.

  • Estrus

This is phase is also known by breeders as ''standing heat'' because this phase is actually when the female dog will stand still for the male to breed. Gradually the bloody discharge seen in proestrus will be replaced by a pink or straw colored discharge signaling this important phase. This phase generally lasts six to ten days.

  • Diestrus

This phase concludes the mating process, as most females at this point will no longer be interested in males. Males however, may still stick around. This phase if the dog has been impregnated lasts generally from the end of the estrus until the birth of the puppies, averaging therefore 60 days. If the dog has not been impregnated, the diestrus phase will not be any different from the anaestrus stage.

This is the longest phase of a dog's heat cycle, indeed it ranges from 100-150 days. It appears to be a quiet time for the dog's reproductive organs, however, the dog's pituitary gland an ovaries are in reality getting ready for the next proestrus cycle.

Heat Abnormalities

  • Split Heat

In this case, the dog's heat is interrupted and then continued at a later time. Basically a female dog will exhibit signs of pro-estrus with the typical bleeding but then once estrus approaches the symptoms disappear for some time.

  • Induced Estrus

It appears that in some cases, the presence of a female in heat may awaken the heat cycle as well in other females.

  • Silent Heats

In this case, the heat is silent, meaning that there are hardly any outward signs suggesting that the heat has occurred.

How Often does a Dog come into Heat then?
Most dogs generally go into heat every six months or better said, twice a year. However, Basenji's and wolf hybris tend to go only once a year.

So at What Age Can a Dog be Bred?

Professional breeders know that dogs should never be bred on their first heat cycle. Rather, the second or the third are much preferable because the dog is more mature and makes a better mother. Of course, only top breeding quality dogs should be bred to decrease the pet over populataion problem.

Breeding Difficulties

-Picky Females

While males seem to have no problem breeding with the female in heat, females on the other hand may be selective at times.

-Multi Sired Pups

If the female dog is allowed to escape she may breed with various males, often causing what is known as ''multi sired litter'' where there are puppies from different fathers.


The complete book of Dog Breeding Dan Rice DVM

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Comments 39 comments

wanda 6 years ago

i have a dashund 7 mo old and she is in heat. she has lost all interest in food...has not eaten in 3 days, but still is drinking water...also she has been trained for a couple months now...and has a couple accidents in the house. im aware that she may be feeling not like herself...but any attempts on feeding her seem futile...when should i become worried and seek vet attn? she is becoming very skinny...should i force feed her some soft puppy food...( i have tried to force feed her some food and she has coughed it up and spit it out) thankyou

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alexadry 6 years ago from USA Author

She should not be not eating for that long. Try to rub some pancake syrup on her gums to try to perk her up. Try to offer her some meat based baby food (with no onions or garlic) if that may entice her to eat but I really suggest a vet visit as this can be a uterine or urinary infection and quite serious if she has lost her appetite for this long and getting skinny. Try to collect a fresh urine sample and take her to the vet right away.

angelgyrl1981 5 years ago

If a female is in heat and bred then her discharge turns a very light pink, and she is still flaging the male, but her backside has went. Back down does this mean that she is not pregnant? Also the male doesn't seam as into mounting her as a few days ago?

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alexadry 5 years ago from USA Author

There is no way to know if your dog is pregnant or not. If she mated at the right time when the bleeding became pink or straw colored and there was a tie chances are high. If the male is not much interested anymore it means the heat is about over. The only way to tell if she is pregnant is by a relaxin blood test or an ultrasound, best wishes!

Susan 5 years ago

My bitch had her last season 9 months ago. Could this be symptomatic indication of infertitly or other problems with her reproductive system? I have checked her every day without fail so I doubt she has had a silent heat, unless it was very very silent! I plan to breed her on her next season but she hasn't had this one yet. She is 4 years old, her mother's seasons were about 6-7 months apart. Her previuos seasons were 6-8 months apart. She is in great health and has several advanced AKC titles.

Thnak you

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alexadry 5 years ago from USA Author

Silent heats are know as silent because there are no obvious signs. Even if you were very attentive you could have missed it. Male dogs however with a nose equipped with more than 220 million olfactory receptors -when we have only 5 million-, would have noticed.

Another case, where a dog does not seem to go into heat after 10 months or more may be due to a health issue suppressing her reproductive cycle. The most common medical causes for failure to come into heat are hypothyroidism, hyperadrenocorticism, hypoadrenocorticism, diabetes mellitus and cancer. If you are concerned, a vet visit may help to check if everything is fine. Best wishes!

SuzieC1 4 years ago

My female is in a pen and I was wondering how much longer she needs to stay there. The male has already tried to mount her and she was receptive. I put her there as soon as I realized she was already in this stage. After she is receptive, how much longer do I need to keep the male from getting to her?

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alexadry 4 years ago from USA Author

SuzieC, if she was receptive to your male calculate she is in the estrus phase which may last about 6-10 days. After this phase is over however your male may still insist on mounting her but she will be reluctant. There are no rules set in stone when it comes to the duration of the heat cycle as this varies from dog and dog, but to play it safe, perhaps keep her at least separated for a week to 10 days. If you can watch her,then you can make her wear special panties that prevent copulation but supervise. I would recommend getting her spayed once the heat is over, this hub may be helpful:

best wishes!

Isis 4 years ago

I have a female large breed dog in heat I have the soonist appointment possible to have her spayed,and my roomate has an unneutered male but we are unable to get either of them fixed before her heat is over,are there any natural alternatives to decreasing this psychotic attraction for eachother in the meantime,it is making things very difficult, and all the world needs are more dogs without a home.Any ideas would be greatly appreciated.Thanks

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alexadry 4 years ago from USA Author

This hub may be helpful to you:

You can always board here until she is ready for surgery if worse comes to worse, best wishes!

tommy 4 years ago

Most of the dogs I own and breed have always went into season around 9 mo.And I have been breeding for 18 yrs.

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alexadry 4 years ago from USA Author

It varies from breed to breed. I have seen dogs going into heat as early as 6 months up to 12 or even more in larger breeds.

manys4 4 years ago

My APBT is in her first heat cycle. She is on day 19. Her bleeding has not lightened. Her vulva isn't as swollen as earlier, but the blood keeps flowing. How long does the bleeding actually last. I have been boarding my male dog to prevent pregnancy. I need to get my other dog home as soon as possible. She will be spayed once a few weeks pass from this cycle.

alexadry profile image

alexadry 4 years ago from USA Author

Each dogs can have different cycles, so there are no rules of thumb. However, generally you will see bleeding for up to 10 days (proestrus) and then the bleeding should fade and become straw colored when she is actually in estrus (when she will be willing to mate) which can last another 10 days. She may still bleed a bit when she ends estrus, but she will lose interest in mating.

Paulina 4 years ago

I have a 2 yr old southern standard American bulldog she was in heat in Feb so she should have come into heat again in August. She has not does this mean something is wrong with her?

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alexadry 4 years ago from USA Author

So dogs have what are called 'silent heats" which can be barely noticeable.

Maryjo 4 years ago

my female dog is still standing after she has mated. is this normal and does it mean shes not pregnat?

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alexadry 4 years ago from USA Author

She will stand for as long as her estrus cycle is active, once over she will no longer allow the male to mount.

Stargirl 3 years ago

I rescued my female on Valentine's Day, nearly a month a go, she was in heat then, i'm not sure for how long. She still has bloody discharge, and it is definitely red, and not pink or straw colored at all. Should I be worried?

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alexadry 3 years ago from USA Author

Do you mean the bloody discharge has been going on non-stop from Valentine's day? how old is she? Any symptoms other than the bloody discharge?

Stargirl 3 years ago

i'm not sure what qualifies as a symptom. she seems healthy (now) aside from that. i'm taking her soon to get spayed, anyway. I'll ask the vet then. she's a little older than a year. the discharge definitely looks like discharge and not like she's bleeding internally. but i'm not a professional.

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alexadry 3 years ago from USA Author

Normally, the discharge is bloody for 7 to 10 days, but as the days go by, it changes to a watery, pinkish-red or straw colored discharge, for about 7-10 more. Generally, after this the discharge should show signs of tapering off. I would have her checked out just to be on the safe side, best wishes!

Naynay 3 years ago

I have a 6 yr old female that mated for her first time is that to old for a bitch to have puppies this was her first heat that she allowed a male to mount her

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alexadry 3 years ago from USA Author

General practice is to not breed a dam that is over the age of 5. The chances for complications get higher as the dog ages. Consult with your vet to check on her.

rach 3 years ago

I have a female we are breeding for the first time, she is over a year old and this is her 3rd heat cycle and I am a registered breeder. I noticed the stages of proestrus and then the bleeding stopped and she became very swollen. She is standing for our male and flagging and she has tied once, but the male is no longer interested in her. They are very playful and she keeps trying to interest him and he seems interested, but he is no longer mounting her. I also noticed her vulva is very dry. Do you have any idea what could be going on?

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alexadry 3 years ago from USA Author

Did you bring the male to her home, or the female to the male's home\? Many males won't perform much if in a different place. Can it be he has some health issue going on? Can you do artificial insemination?

Kristen 17 months ago

I have a 4 year old schnauzer/chihuahua mix. She startes her cycle about 14 days ago. She has stopped bleeding and discharging for the most part. I also have a year old puppy which is actually her son and he was all over her for days but he has lost interest and they seem ro be back to normal. Does this mean her heat is over? Im wondering if I take off her diaper ans his wrap(diaper like thing rhat covers him up)...?!?!

Kristen 17 months ago

Added to last post...I just dont want her to get pregnant!!! long after her heat is over can I take her to get fixed!?

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alexadry 17 months ago from USA Author

When there's a loss of interest, generally the heat is over, but doesn't hurt to keep the wraps on an extra day or two to make sure or at least supervise closely the two. A dog can be technically spayed even when in heat, but it costs more and is more complicated as there's more swelling and bleeding involved. I would give your vet a call and ask him/her directly for advise on the exact time frame as they seem to have different protocols.

Gill 5 months ago

Hi my border terrier had a failed attempt at breading 11weeks ago, but has now started to bleed again and vulva is swollen, she normally comes in every six months, what does this mean? many thanks

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alexadry 5 months ago from USA Author

You should see the vet as soon as you can as it can be a sign of pyometra or a urinary tract infection.

Jacque 3 months ago

I have a 3 yr old female Rott and a male Rott, Both intact. We had tried to breed, with a full tie a couple of times each cycle, since she was 2, but no luck. Her last heat was in January and we took them in to the vet to have our male check out first. It turns out he is infertile. I located another intact 3 yr old male, that's owners have been wanting to breed. I noticed that our male was paying extra attention to her a couple of weeks ago. Her vulva had not swelled and she did not start to bleed until a week ago. I was watching our male to gestimate when she was fertile. His behavior has always been obvious. He had not tried to mount her yet, so I decided about 4 days ago to take her into the vet and have him check her. He did a vaginal smear and said she was at the tail end of her estrus. About 2 days left. He told me to take her directly to the other male, and try multiple bred dings over the next 2 days. I took her there end she seemed to be receptive to the male, but would not let him mount her. He is a little more timid than our male, and she started getting snippy with him every time he tried. He did however penetrate her for a short period, but no tie. I took her the next day, same thing, she flagged him but he seemed a little reluctant. They just hung out and played all afternoon, but we're fairly mellow. I did not take her back the 3rd day, assuming we missed the mark. Yesterday, 4th day since the vaginal smear, my male started acting anxious and trying to mount her. She was flagging him and let him mount. I pulled him off before he was able to penetrate and separated them. I took her back to the other male and she seemed receptive to him, even backing up to him, but would not let him mount. I noticed last night she was bleeding again now a little bit lighter. Slightly red in color.Today she has been hot and cold. Flags our male and allows him to mount, she has pants on so no penetration, but then later she growls if he is bugging her. This has been off and on all day? Should I try to take her back to the other male or would it be a waste of time? According to the vet....she should be done ovulating by now. I don't know if she is having an off cycle or if my males timing is off. Also could she just not want the other male because she is used to our male? She usually is not this moody. She has been sulking and acting very hormonal the last couple of days.

Shelagh 2 months ago

My female GSD has just recently started showing signs of heat and my male agrees with my thoughts. However, within 3 days he has almost completely lost interest. He is usually quite energetic in his displays with the girls, so I'm wondering, could she be done already? It's literally only been 4 days! This is her third heat, she just turned 2. Her last heat seemed short to me too, but as he wasn't allowed near her,I I didn't have his confirmation. Open to thoughts!

Kristi thomas 8 weeks ago

We rescued our pit bull about 2 months ago. She came in heat about 5 weeks ago and after the 10 day cycle she stopped and was mated by our other pit and now she has started bleeding again. It has been 3 weeks now of non stop bleeding. Any helpful hints???

Ezekiel Guzman 7 weeks ago

I have my dog female 7 months old she has the first heat (menstrual period ) but she is being bleeding for almost a month I think she is already weak she eats but she can't stand the dried food what can I do to help my dog??

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alexadry 7 weeks ago from USA Author

That's not normal Ezekiel, please see a vet.

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alexadry 7 weeks ago from USA Author

Kristi, that does not sound normal, would see the vet, as soon as possible..

Shiba5 5 weeks ago

Hi I have a female that goes through the normal stages of heat except for the fact that her bloody discharge never goes straw coloured. It just stays the same red colour maybe a little lighter in colour but just gets less. Is it still ok to breed her?

Eliz 25 hours ago

My golden retriever is in her second week of her season, she just has a slight discharge but her tail and feathers are always soaking with urine, she had this problem the last season too, this is her 4th season she'd not great at keeping herself clean possibly because we had doggy pants and pads for her the first 2 seasons but there's no point this time or last time as she's so wet!

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