dogs on heat square

What Is Dog Heat and How Long Is a Female Dog In Heat For?

Whenever we hear of a dog in heat we conjure up images of creatures acting in a very awkward to watch manner. But have dogs in heatyou ever wondered about the chemistry that puts into motion the all-important act of procreation in our canine friends? You might actually be surprised to find out that we have a lot more in common with our furry friends than we care to admit.

Just like humans feel sexy when they’re ovulating, a bitch experiences her heat cycle when she’s ready to mate and become pregnant, an experience she undergoes every six months or so known as estrus.

Why It’s Important To Know When Your Dog Is On Heat

If your female dog is unspayed, knowing when she’s in heat can help in managing her reproductive cycle. All you have to do is look out for tell-tale signs of changes in personality or loss of appetite and take the appropriate action. Such knowledge can also save you from making expensive trips to the vet for a health diagnosis.

When Does Heat Start and How Long Does It Stay In Heat?

On average, the heat cycle for dogs takes 21 days or between 2 to 4 weeks. The age by which female dogs go into heat varies from as young as four months – in smaller breeds – to about six months old. Some giant breeds take as long as 18-24 months old to enter their first heat cycle. Dog experts generally frown upon breeding of young female dogs during their first and second heat cycle as their ovaries are considered to be immature.

A dog’s heat cycle can be broken down into four stages:

Stage1: Proestrus

This is the initial part of the heat cycle which can last anywhere from seven to ten days, with most bitches typically going through nine days. Proestrus indicates that your dog is preparing for pregnancy, although she will not want to mate with a male at first.

  • The first sign that many vets will warn you to look out for is the swelling of the vulva. During this time, you’re also likely to see the following changes in your dog:
  • A change in personality: You may notice your bitch become more affectionate towards you, while at other times she appears aloof or edgy.
  • Change in appetite: It’s quite common for a bitch to lose interest in food during the first week of the estrus cycle, although the opposite is true for some dogs. Those that experience a rise in appetite exhibit strange behavior like scavenging for food in the bin.
  • A swollen vulva: Different dog breeds have different levels of swelling of their vulva. It’s slight in some, while in others it is quite noticeable.
  • Bloody discharge emanating from the vaginal area.
  • Tucking of the tail: Dogs tend to guard their vulva by tucking the tail between their legs or by sitting down whenever another dog approaches them.

Bleeding poses a number of challenges for the pet owner, but there are ways you can cope with the situation and keep your home clean. Although your dog will clean herself, you may still find blood spots splattered everywhere especially if she shakes her body. If you have wooden or marble floor, it isn’t too difficult to clean up with a mop, however, if you have a carpet you may want to put towels down for her.

Stage 2: Estrus

pregnant dogs after being on heatThis is the period when the ovaries of your dog begin to release eggs in preparation for fertilization and is similar to a woman’s menstrual cycle, the only difference being that it occurs twice a year.

The fertilization window is relatively small during the heat cycle; it can start nine or ten days after she’s gone into heat and lasts about five days. However, the fact that a male dog’s sperm can survive for up to one week in her uterus, makes it possible for your dog to become pregnant within a few days following intercourse.

Estrus can be a tricky time as your dog is prepared to mate with any male, while every male in the neighborhood is interested in her. If you want to keep her from mating, you may have to take extreme measures such as locking her in the house. Don’t let her out in the yard or leave her on her own, otherwise, she may find an escape route under or over the fence.

The symptoms to look out for during this period include:

  • A lighter colored discharge: the discharge now turns to a pinkish-tan stain from the previously bright red color.
  • Softening of the vaginal area: initial swelling reduces and the vulva softens up to ease penetration.
  • Flirting accompanied by tail flagging: the bitch now changes from tucking her tail to keep males away and now begins to flirt openly. One of the most obvious signs is welcoming the male to mount by turning her rear toward him and keeping her tail out of the way. She may even fan it lightly to attract him to her scent.

Once estrus starts, it may take some time before the heat cycle becomes regular. For some dogs, this can be as much as eighteen months. For dog owners, it’s a good idea to take note of the cycle during these early days.

Stage 3: Diestrus

Diestrus signifies the end of the fertility window in the heat cycle. The uterus walls thicken and in some cases, a dog may even experience false pregnancy during this time. False pregnancy is accompanied by symptoms like enlarged mammary glands and milk production at times.

You can tell it’s the end of the heat cycle by looking out for the following signs:

  • Reduced vulva swelling: It takes about a week for swelling to go down. However, the vulva may remain a little enlarged after the first heat cycle has passed.
  • Loss of interest in male dogs: Whether she breeds or not, the bitch loses interest in mating and therefore stops flirting.
  • Tapering off of discharge: The pink colored discharge released during estrus turns back to red, and gradually reduces in the final week.

If breeding was successful diestrus can be prolonged over the 63-day period of the average dog pregnancy.

Stage 4: The Resting Stage – Anestrus

So long as no pregnancy results from mating during the heat cycle, your dog goes back into the anestrus state, a five to eleven month period of inactivity that finally cycles back into proestrus to start the whole process afresh. The anestrus phase lasts around 15 weeks.

How to Stop the Female Dog Heat Cycle

Unlike humans, female dogs experience estrus for their entire lives, although the period between the heat cycles keeps lengthening as they age. Female dogs, therefore, don’t experience menopause, which is why spaying your dog is so important. Puppies that have been spayed do not go through estrus; but apart from preventing unwanted pregnancies, spaying confers numerous other health benefits to a canine. Not only does it prevent life-threatening conditions like mammary cancer and uterine infections, it also reduces other risks like her running off and getting injured in a road accident when she’s in heat.

Some of the methods you can use to stop the heat cycle include:

Use of Medications

If you’d rather not sterilize your dog, you can get a prescription from a vet to suppress her heat cycle. Gonadotropin-Releasing Hormone or GnRH drugs are commonly used and are available as subcutaneous implants or injections. Although they’re highly effective, the drugs do come with some side effects, including enlargement of her tits, behavioral changes, and weight gain.

Stopping the Heat Cycle Permanently

Unless you intend to use your dog for breeding, you should seriously consider having her spayed before her first heat cycle. Since it’s difficult to tell when this will be it’s prudent to spay a dog before she gets to the age of 6 months. Spaying removes the uterus which reduces the risk of developing pyometra, a fairly common and life-threatening disease of the uterus. It also prevents other complications like perineal fistulas, which are associated with delivery.


Paying attention to signs of dog heat is vital whether you’re breeding or you want to prevent mating from taking place. By understanding and timing the cycle you can prevent an unwanted pregnancy and the diseases associated with it, or enhance the chance of a successful whelping process by your dog.

About the Author Andy

When not writing about himself in the third person, Andy spends much of his time walking his dog Mr Wox, aka Soxy Woxy. A leading authority on dog-related topics, Andy is highly respected, deeply appreciated and widely admired.

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