Dogs in Heat: 9 Things to Know

Let's talk dogs in heat — What should you do if your dog is in heat? And what are the signs of a female dog in heat in the first place? Do dogs know when they're in heat?

A female dog with a pink ribbon.
A female dog with a pink ribbon. Photography by Claudio alexandre Cologni/Thinkstock.

Do dogs have periods? Not the same way that female humans do. Female dogs who aren’t spayed go into heat and the amount of time a female dog bleeds and when she’s fertile varies greatly from a human menstrual cycle. Let’s discuss some facts about dogs in heat — and why it’s important to spay your female dog!

Maltese dogs with ribbons in their hair.
Do you know these important facts about dogs in heat? Photography ©Cynoclub | Thinkstock.

1. A dog heat cycle only happens once or twice a year.

The canine estrus cycle (commonly referred to as the dog heat cycle) occurs every 6 to 12 months.

2. A puppy can go into heat sooner than you think.

The earliest that most dogs will experience their first heat cycle is at 6 months of age.

3. Dogs in heat should stay away from intact male dogs for 3 to 4 weeks.

This means that dogs in heat should not visit dog parks or do any doggie day care visits. “Anytime a dog is in heat, assume it’s going to be at least a month and keep them away from male dogs during that time,” says Nancy Kelso, DVM, medical director at VCA Columbia Animal Hospital at Hickory Ridge in Columbia, Maryland. “Generally, neutered males are fine, however, it’s also stressful for intact males to live in the same house as a female in heat so we usually recommend totally separating them.” If possible, send one of the dogs to stay with a relative or friend for a month or so.

4. Don’t think you’re in the clear once the bleeding stops.

With dogs in heat, each dog heat cycle lasts 3 to 4 weeks, but you will only see bleeding during the first 2 weeks. “The fertile period is actually when the bloody discharge starts to subside and it becomes pink or clear and there’s much less of it,” Dr. Kelso says. “Even the swelling of the vulva goes down substantially so a lot of people think the dog is out of heat, but no, that’s actually the prime fertile time.”

Dog pants, like this fun polka-dot option from Glenndarcy, are good for dogs in heat.
Dog pants, like this fun polka-dot option from Glenndarcy, are great for dogs in heat. Photography courtesy of Glenndarcy.

5. The bleeding from dogs in heat isn’t as bad as you might think.

“Fortunately, in most dogs it’s not a large amount, it’s relatively small,” Dr. Kelso explains. “Some people will use sanitary diapers for dogs.” With some dogs in heat, you won’t really notice the bleeding. 

6. Don’t delay scheduling your dog’s spay.

Many people don’t ever experience dogs in heat since it’s best to have your female dog spayed prior to her first heat cycle. If your new rescue dog goes into heat before you can get her spayed, your vet might suggest waiting until she is done before spaying her. “It can be done while they are in heat or immediately after, but it’s not the ideal time because the uterus is much larger and much more vascular at that time,” Dr. Kelso says. “If we have the luxury of time, then the perfect scenario is we wait about two months after they’ve been in heat to spay them, but if we need to get it done because they’re getting adopted out then we’ll definitely spay shortly after heat or when we need to.”

7. Spaying your dog decreases her chances of developing mammary cancer.

Mammary cancer is the equivalent of breast cancer in dogs. Check your female pup regularly for lumps in her breast tissue (from her armpit to her groin). If you feel something suspicious, schedule an appointment with your vet.

8. Pyometra is another danger for female dogs who aren’t spayed.

Pyometra is an infection of the uterus. It can be deadly and almost always requires an emergency spay surgery. If the infection is “open” (meaning the cervix is open) it can be easier for veterinarians to diagnose because there is usually foul-smelling discharge from the vaginal area. “Dogs can also have a variety where the cervix is closed, so the pus is actually building up inside the dog and those dogs get really sick,” Dr. Kelso says. “They don’t eat, they don’t drink and they run a high fever. If you see any of those symptoms, you should bring her in to a veterinarian.” 

9. Dogs in heat know when they are in heat and fertile — and when they are not.

“Dogs know when they’re ready to be bred,” Dr. Kelso says about dogs in heat. “They get a little more flirtatious. Sometimes they might be a little grumpy at the beginning of heat. If a dog tries to mount them or something, they’re basically saying, ‘I’m not ready.’”

Thinking about keeping your dog intact? Read this first >>

Thumbnail: Photography by Claudio alexandre Cologni/Thinkstock.

This piece was originally published in 2017.

Read more about dogs in heat on

94 thoughts on “Dogs in Heat: 9 Things to Know”

  1. My. 7 month old Pitbull is in heat and she is bleeding ALOT. So if anyone else is experiencing this don’t be freak out like I was after reading this article . I took her to the vet (which I never mind) and they laughed because I was crying . There’s a lot of wrong information and missing information in this article . Just always call your trusted vet .

    Good luck . And be prepared . I was not and thought it would just be a little spotting . Boy was I wrong ??‍♀️


    1. Admin, please just shut up.
      Or give ONE Comment at the top That
      “Applies to ALL Health Issues below”

      I’ve come to Hate your face.

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  7. This article is not informative of the health risks involved with spaying your pet vs. leaving intact. The fear factor is evident in the scare tactics that are revealed ..what will happen and risks if you don’t spay your pet. I strongly advise finding valid research on this topic, before buying in to what appears to be an article written for the benefit of Veteraniarian Clinics, and scaring pet owners.

  8. People are always pushing to get your dog spayed/neutered as soon as possible. I had to really dig around searching for the cons of doing this. We neutered our male Doberman early. He died of one of the negative effects cited as a cause of early neutering. The health risks of not waiting a year or two are increased for a number of issues, his being osteosarcoma. If I had known his chances of dying from bone cancer were increased by doing this I definitely would have waited. I lost a fantastic, super special member of my family by doing this too early. Pet owners should have the opportunity to be informed of both the positive an negative effects of the surgery so they can make an informed decision about what and when. There is such a heavy emphasis on getting it done soon, but not much ever said about what could go wrong. My sister lost a Weimeraner girl during her spay surgery. It was quite traumatic. Let’s put all the facts out there.

  9. Let’s not forget the fact that spaying or neutering your dogs and/or cats in Norway and Denmark is illegal.

  10. I am a little confused. This site seems to try and answer some of the questions asked but has no idea about others. Some of the answers are ridiculous. If i wanted to go to my vet and pay a vet bill I would not be on the internet searching for answers. So basically I feel i just wasted 30 minutes reading “go ask your vet”.

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  12. Candyce Carlstrom

    What if discharged is alot for a 16 month frechton and very dark red that it looks like a murder scene should i be worried cause today is the first time thats happened ever

  13. My one dog i waited till she was 4 and had her fixed and it put her right into a thyroid problem…why did this happen
    Now im afraid to have my female dog fixed because i don’t want her to go into a thyroid problem

    1. I don’t get the neutering push. If a human female has a hysterectomy they can take hormone replacement to maintain health. So we just neuter a dog and wish them luck?

  14. This is the most uninformed “dog” website I’ve ever seen. Do your research (from more than one source) before siting or believing “facts”.

  15. My female Boston Terrier has finished bleeding for about a week and a half but her teets are still swollen. Is this normal?

      1. Admin, please just shut up.
        Or give ONE Comment at the top That
        “Applies to ALL Health Issues below”

        I’ve come to Hate your face.

  16. Wow…it’s scary what you can find on the internet these days. Spaying your dog before their first heat cycle is like a human getting a hysterectomy before going through puberty and getting their period. How do more people not realize how unhealthy that is??? I don’t spay/neuter before 2 years old, regardless of breed or size. There are far more health benefits to waiting a couple years than there are to spaying at a young age.

  17. I am greatly disappointed by the lack of scientific information in this article. Anyone who is keeping up with the latest scientific information regarding the best age to spay or even if it is in the best interests of the health of our dogs, knows that this article is NOT presenting accurate information. I agree with a previous comment that this is an attempt to “shame” dog owners into spaying prior to the first heat cycle. Because this is apparently an opinion piece which i not based on scientific fact…and yes, I am interested in the “facts”, I will no longer subscribe to this site.

  18. I don’t usually read all the comments but I did. Seems everyone at work got a puppy recently so this has been a topic of conversation for a few months. I have a male and a female, brother and sister, chihuahuas. My little girl went into heat and I was concerned. They are so use to being together all the time. Needless to say she has made it thru and no puppies here. I’m glad I didn’t get her spayed yet and will wait at least one more cycle. It’s funny how all the comments that were made and no response was made. And the ones that did get responses were, “ask your vet”. Really? If you’re an authority on dogs, enough to write this article, you should be responsible enough to respond to some of the issues brought up.
    I think…you should Not be publishing articles you can’t stand behind. You know what they say about opinions….

  19. Is it normal for my dog not to eat when she’s in heat she’ll eat wet food but not her regular food and she’s starting to pee in the house

    1. Hi Magda,

      Thanks for reaching out. Please spay and neuter your dogs.

  20. waooo 🙂 Its summer in my country and i was worried about how to take care of by Red Tiger Bulldog. this really solved my problem, Thank you really appreciated.

  21. Sherif Youssef

    My lab 8 years old on her period for more than 7 weeks now! Is this normal or I need to visit the vet?

    1. Michaela Conlon

      Hi there,

      Thanks for reaching out! Here is an article for more information on dog’s periods:

      Do Dogs Have Periods?

      We suggest contacting your vet for more specific information about your dog’s condition.

  22. My dog aalish she is indian bread actually we all live in india here is happening so heat. now so I think my dog she is bleeding now a days.
    I think it’s all happened bcz the heat .
    Can you any one sujest me what can I do fir it.??
    Plz help me.

    1. Michaela Conlon

      Hi there,

      Thanks for reaching out! We suggest contacting your vet ASAP about the bleeding. Hope your dog feels better!

  23. Let’s also not forget how bad it is for the stomach muscles of young pups to be spayed too young!!! Hate how one sided this is. I plan on waiting to spay for many health reasons.

  24. Dogs should not be spayed before their first heat. They produce hormones that are essential for growth, maturing, general well being and longetvity. Spaying should be held off for as long as possible.

  25. My schnauzer’s breeder – who breeds and shows champion show dogs – told me to wait 2 heat cycles for the reasons already listed. I asked my holistic vet, who suggested 3 cycles. She said people are told to spay and neuter so early to help with the overpopulation of unwanted animals by irresponsible owners, but it is still really bad for the dog.

  26. Margaret,
    Giant breeds take much longer to mature. Waiting until 2 gives your dog time enough to build the necessary bones and muscles to handle his mature weight. My female Pyr actually continued to grow until almost 4 yrs old, although not at the rate that she grew as a younger pup.

  27. Margaret Sullivan

    I recently got a male Great Pyrennes puppy at 10 weeks old. I have all my animals, dogs, cats and rabbits neutered [2 female cats, all the others male]. I was told by the breeder under no circumstances should my new boy be neutered until he’s 2 years old. A friend has an 8 month old Leonberger and she was told exactly the same thing by the breeder. This lady always neutered/spayed her dogs and cats at 6 months old.

    1. My vet suggest 4-6 months for my Male dog and he has no problems my female boxer was 9 months old and had never been in heat my vet recommend to have her spayed as she was hit by a car and her pelvis was broken and her hip was dislocated she was put back together with screws and wires so he suggested she never be able red because he did8think she woul8be able to carry puppies to term so when he was putting her back together we said just do it all in one operation and she is the most laid back chilled boxer I ha ever e ever seen. She loves children and if they bother her too much she just gets up and walks away from them. She is the best dog ever!!!

  28. Anne Crutchley

    Thank you good advice however what is the best thing to do if my dog is mated accidently and I do not want the puppies when should she have a pregnancy test?

    1. You asked what if “your dog mated accidentally?” Seriously, be a responsible owner and refrain from public places, walk with leashes only, avoid dog parks! Take responsibility!!!

    2. There is a “day after” shot for dogs. I have a female who just had a pup on her last heat cycle. She was just shy of being one year old and our male got her and we didnt even know she was pregnant. Well, on her next heat, my idiot bf kept leaving them together and our male got her again, I called my vet and scheduled an appt and got her the shot. Thank goodness, no puppies this time. But one of the risks is infection, which she did develop. Took her back to the vet and he gave her antibiotics, and it cleared it up quickly.
      Hope this helps.

        1. I would definitely get rid of the bf! Our dogs are our best friends and family members. My animals are my babies because they depend on me for their food and care. So your boyfriend is showing that he does not care for your furry baby is saying a whole lot more than you realize. I choose man over dog once. And will not make that mistake ever again. I was young and didn’t see the sign or more likely choose to ignore it at first. Shame on me. I still miss that dog! The dog was right about him by the way. They Truely are better judges of people & try to watch out for you IF you let them. Ps my girls have all been intact purebreds and very clean. First because Iwas thinking of possibly breeding such fine animals. But life keeps you busy and before you know it, I haven’t yet bred any of them. My girls are Very nurturing to my children also. I think this is better in intact females. Mine treat my children as their own. I personally think that their motherly instinct is better left with those hormones flowing naturally. So if you have giant breeds around children you might want to keep them that way but be ever vigilant during the early summer or whenever your dog goes into heat. You wouldn’t want your children or yourself to have to get in between all that very intent muscle!! I wouldn’t trust an ice cold hose to stop it either. She guards us 12 mos/yr. We can guard her for one month/yr for all her loving devotion.! ?? and also my rottie made it healthy to14yrs , American bull 7+?bull mastiff 8+?, and now cane Corso just having her first cycle now at 8 months. However this one continually has had health problems right out the gate, mostly skin and bladder issues but never had this many problems with any other dogs so fingers crossed and vet bills a mounting. We shall see. He too was pushing for fixing her when she wasn’t responding to my anti aggression training, but I stood fast and she’s now on a med and all is well. She’s definitely costing me allot and she’s still so young, 100lbs & growing.

          1. Thank you for sharing about your cane corso. We are experiencing her first heat. How do we deal with keeping she and the house tidy?
            Finally, thank you to all who weighed in on waiting to spay large breeds. We will definitely wait. Glad I read through all the responses. Will postpone her surgery.

        1. Amen. And so irresponsible if you don’t ever want puppies. An intact male and in heat female should NEVER even be in the same household during that time. I don’t think you should be judged for not wanting to put one of them through a surgery. But why, then, would you get a male and female to live in the same household?

          1. they can for sure be in the same household. it’s called crating your dog and keeping a watchful eye on them both. crate and rotate

      1. I asked my vet today (9/20/2019) about the shot to terminate puppies because I didn’t want non-purebred puppies, and I was told that no vet provides that service anymore because the females had a high mortality rate from affects from the drug. I was told to either spay her or let her have the puppies – no other choices.

  29. My dog was in heat a month-and-a-half ago can a dog go back into heat right afterwards because she seems to be back in the eat now

    1. Hi Lori,
      Thanks for reaching out. We suggest reaching out to your vet to see what’s going on — and also schedule her for a spay ASAP.

      1. Spay spay spay, every suggestion to spay or neuter is wrong. I understand some people believe in spaying and neutering. But I’ve only seen one post that asked questions. I pulled up this site for information on the heat cycle specific to Dobermans. I haven’t found any helpful information on what I was looking for. It seems everyone voicing an opinion to spay. We are breeders and regularly research the internet to see how much misinformation is out there. Find more than one Veterinarian you trust and go to them using what advice they give to make your final informed decision. I recommended finding more than one Vet, ex: as a person a female if you were told by one doctor you needed a total hysterectomy would you get a second opinion? As responsible pet parents do the same. Get a second even third opinion especially when it comes to spaying and neutering. You can’t put back what you take out. There are breeders clubs every where find one for your breed of dog and ask questions. I’m shocked by the advice to spay/neuter without any background health information by people who do not hold a DVM degree. Each dog is unique in that a complete health check up and tests should be the determining factor. Talj to a professional and research, research, research.

        1. I feel the same way about spaying and neutering as I do all the shots they want to give the dogs, and for my dog’s breed it’s always followed by an emergency intervention (that will be $300) when the dog starts crashing and has to be revived. We are doing titers until the tests indicate they no longer have immunity to something that could make them sick. I do not plan on spaying my female unless there is a problem and then will do the partial spay. Too many PC
          warriors out there trying to run the show.

  30. This article screams “shame on you for allowing your female dog to go into heat!”
    I have a nine month old female Great Dane that I plan to go thru 3 heat cycles before spaying her. Why you ask? For her optimal growth and health. Why did this article not mention the side effects of spaying too early? Incontinence is a biggie for females spayed too early. How about pointing out the facts on how long to wait after the heat cycle before spaying? This is an important factor in regards to possibly dying due to internal bleeding. Why did you not mention how important it is to hold off spaying for a giant breed so the growth is not stunted?
    If you are trying to shame people..shame on you!

    1. We had a female westie that we spayed when she was about 6 months old. She developed health issues and was never a very healthy dog. We learned from our mistakes, however, and now have a 7-year-old westie that has NOT been spayed, and we don’t plan to spay her. Her estrus cycle comes about every 10 months and has never been a problem since we are responsible pet owners. We also feed her a healthful, homemade diet, which consists of a lot of fresh meat, organ meat, certain vegetables, eggs, and species-appropriate vitamins. She is vibrantly healthy with no issues whatsoever.

      Anyone wanting a healthy dog should do some research before spaying. Don’t just buy into what you’ve heard. Spaying female canines is not common in other countries, and if you do a little digging, you’ll find that not spaying doesn’t necessarily cause pyometra or mammary disease. Those are MYTHS.

    2. Carol Shirley-Browne

      Exactly, I have a vet that we have used for over 40 yrs. When I got my yorkie mix, he told me to wait till she had her 1st heat cycle and wait 3 months after. At first I wondered why wait that long but, now I understand the reason

  31. This article heading is misleading and lacks accurate veterinary information. It reads more like a spay your girl now campaign.

    I’m disappointed that a writer for this website lacks facts and promotes an agenda. ????????

  32. Agreed. I have a large breed (Alaskan Malamute) and two very reputable vets who specialize in large breeds have both said one or even two heat cycles will help with her growth and health later in life and they are less concerned about the mammary tumors – but they do say one – two heat cycles is enough and no more – a way of minimizing the risk.

  33. why don’t you include all of the health risks there are to female dogs spayed before their first heat cycle so people can make a truly informed decision?

    1. I completely agree! My vet said to wait until until a minimum of one heat cycle (best is two in his opinion) before spaying for developmental reasons (the ovaries and uterus both secrete hormones as the dog develops from a puppy into an adult).

      Also, I don’t know if this is true (and correct me if I’ve been misinformed), but a friend that watches dogs told me that spaying smaller breeds too early can affect their development to the point of lifetime incontinence.

      After thinking about it a little, we decided to wait…it’s really not that bad…it’s a month of keeping her away from intact dogs. When it’s time, we will opt for partial spay (keeping the ovaries).

      1. Exactly! We adopted a rat terrier and after a good bit of research discovered a vet in our area who did the ovary-sparing spay. It was more costly, but when you look at the potential problems from a traditional spay (which amounts to a full hysterectomy and leads to problems like Cushing’s disease, obesity and ill-temperament due to the adrenals glands being forced to overwork to make up for the lack of growth hormone from the removed ovaries), it’s pretty much a no-brainer. Another side effect that seems to result is a reduced lifespan.

        99% of vets have been programmed to say that keeping a dog intact will inevitably lead to cancer, because they don’t know any better. One vet I spoke with didn’t even know about the ovary-sparing procedure!

        There is information out there on ovary-sparing spay folks. Find it and make an informed decision!

        1. The worst side affect from not doing s/n is having accidental litters. In the world of animal rescue 30+ years ago that meant that 25 million animals were killed due to overpopulation every year in this country. While that number is down to about 3 million now that is still far to many. Please take care to not add to the deaths of millions of animals by fixing your pets.

          1. Very well said. It is unacceptable to allow dogs to breed just so the kids can witness “the miracle of birth”. In my mind, there is no such thing as an accidental litter for a house pet. It’s irresponsible pet ownership.

      2. I’ve only owned small breeds and all have been spayed when they were 5 months old BEFORE their first heat cycle. Not one of them were incontinent! Spaying dogs before their first heat cycle greatly reduces their chance of getting mammary cancer. Waiting until after their first heat cycle to spay them is an extremely old and out-dated technique.

        1. My moms poodle became incontinent after being spayed at 6 months. So it’s not out dated info. It still happens

        2. It’s far more common for large breeds to have issues with incontinence. Also – the updated info on spay/neuter is that it is generally far better to wait until the dog is older (18months – 2yrs). Of course, small dogs are less affected by the majority of health issues caused by early s/n so of course your experiences have mostly been positive thus far.

        3. Standard Poodle mom

          It is not old and out dates and any vet worth their weight will tell you for LARGE breed dogs you should wait until after their 2nd cycle so that the hormones will help fuse the growth plates. Which helps prevent your large breed dogs from developing dysplasia.

      3. I didn’t even know this was an option, although I have certainly wondered about it, since a complete hysterectomy in a human puts her into menopause. So what does that do to a year old female dog? I am SO SO glad I read this. My vet believes in waiting for spay/neuter if the owner can be responsible about it. I will definitely ask about keeping the ovaries

      4. Christina Jimenez

        My Pomeranian puppy just died from a spaying procedure. She was 6 1/2 months old and weighed 5.5lbs. She had unexpected bleeding and they had to repair a blood vessel. She never recovered from surgery and I never saw her again.

    2. My dog went into heat AFTER having her “fixed”. I had no idea what was wrong with her. Can you imagine?! Turns out it was the Vet that was shady. I had to hire an attorney to recoup fees of having to have her spayed… AGAIN!

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