When is a Dog in Heat Or In Season?


When you have a female dog and you’re concerned if she will end up pregnant because other dogs are taking an interest in her, it can be handy to know whether or not she is in heat or in season (the terms both mean the same thing) and if she is, when the seasons cycle might finish.

How do you know when a dog is On Heat or In Season? The best indicator that your dog is ‘on heat’ or is ‘in season’ is the swelling of her vulva, it will be larger than usual, followed by a general behavior and mood change toward other dogs. She will also display other physical symptoms that come in phases such as bloody discharges and increased urination, a drooping tail and overt licking of her genitals.

In this article, we give you the answers related to questions about a dog being in heat. We show you the signs to look for and the different stages of a dog in heat. You will also learn how the behavior of your pet changes when she is on heat and how you can take care of her.

Dogs in Heat, the general info

The first thing to understand is that all mammals experience periods, from the the human female to the Fruit Bat. However, the dog’s period is a little different from that of a human. A dog’s first season can be a pretty messy and turbulent time for pet owners and pets alike.

Your dog may be confused by the bleeding. and while she is licking to clean herself, you as her owner may be a little repulsed. Do not stop her though, this process is very natural and necessary.

Don’t tell your dog off for licking/cleaning herself

If you have decided not to have your pup sterilized or plan to breed her, then this is an inevitable stage that you must go through.

The age at the first heat cycle tends to vary significantly between the various dog breeds. Toy breeds can experience heat for the first time when they are as young as four months, while giant and large breeds may reach the age of two before experiencing their first heat cycle.

On average, however, most dogs will experience their first heat cycle between 6 and 15 months. The same also generally applies to the regularity of the dog’s periods. Initially most dogs will have irregular periods to start and this is quite normal, the cycle then usually normalizes within the first two years.

When will my dog have her first season in heat?

Your dog comes into heat when still a puppy assuming that you have not had her spayedOpens in a new tab.. Toy breeds may experience it as early as four months, while giant breeds may possibly be delayed until their 2nd year.

In general, the first heat cycle is usually very mild in its appearance, in fact you may not even notice it unless your front yard becomes a popular gathering place for male dogs from the neighbourhood.

This timeframe when she enters her first heat cycle is an indication that your female dog has reached puberty and thus is maturing sexually. She can now conceive, become pregnant, and bear puppies.

However, nearly all breeders and veterinarians recommend that you wait until the dog has gone through one or two heat cycles before you allow her to breed. Breeding her while she’s still too young can have an adverse effect on her and any puppies.

How long are dogs in heat?

Usually, the heat lasts around 18 days, although it can be slightly longer or slightly shorter, dependant upon the breed. Most female dogs come into heat every six months or so (twice a year), although again the interval between breeds can vary. Small breed dogs might cycle up to three times annually, while giant breeds may cycle just once every 12 months.

As I said earlier when dogs first begin to cycle, you can expect their cycles to be rather irregular. The irregularity can last for up to two years before she finally develops a regular cycle and the ‘in heat season’ can happen at any time of year.

The general exception here is for Tibetan Mastiffs, Basenjis and some Wolfhounds, which sometimes cycle just once during the spring time, speculation would suggest that this timing is a genetic circannual breeding rhythm trigger, possibly dating back to when some dog breeds were only having a short window of opportunity with a safe time of year to meet and breed, similar to that of bears for instance.

Bears meet up once a year to mate.

Notable Changes While in Season

Personality changes

If the you are in tune with your dogs behaviour, some of the first signs you may notice are a few changes in her demeanour. Your dog may be shy or quiet, nervous, or possibly more friendly than usual, or even become aggressive. Each dog will react differently you really cannot tell how she is going to act.

Some dogs may have swollen nipples. For several days, before she starts spotting, she will urinate at every chance she gets when outside, this is her way of alerting male dogs that soon she will be ready to breed.

Dogs in heat are generally inclined to be more receptive to company. She might display strange sexual behavior such as mounting other dogs or even your furniture. Some female dogs may become more commanding or domineering during their season. Yet others may look anxious and even display maternal characteristics like gathering toys in her sleeping area or bed.

Spotting in Season

Your female dog will begin “spotting,” this is a bloody discharge coming from her vulva. If you happen to notice it you may consider this as her first day of heat. The spotting can be just a few drops or a lot, but it will always decrease as her ovulation time approaches. The ovulation period can be anywhere from 1 to 3 weeks after her bleeding starts.

One of the reasons you may want your dog spayed (more on that later) is bleeding indoors and making a mess on the house furniture. If you don’t wish to have your dog spayed for some reason but don’t wish to ban her from the house, you can get doggie diapers that will cover her up so that she doesn’t stain the furniture or carpet.

Doggie Diapers
Doggie diapers can help prevent mess on the furniture

Tip: You need to remove the diapers every time you take her for a walk because if you don’t, she will urinate in the diaper and ruin it.

Stages of the Heat/Season Cycle

A female dog will stay in heat for around 21 days. The heat cycle’s length can vary between dog breeds or even from one cycle to the next. Dogs will have their first heat or reproductive cycle upon reaching puberty. Each cycle has several stages; the second stage, estrus, is perhaps the most significant as this is when she can become pregnant.

Proestrus – (Stage 1)

The first dog heat stage is called proestrus and can last from 3 to 17 days, although many experience about nine days. The most notable sign of the proestrus is the swelling of the vulva, which is also one of the best ways of knowing the dog heat cycle has begun.

Common symptoms that you will notice during the proestrus stage include:

  • Swelling of the vulva
  • Personality change
  • Appetite changes
  • Tail tucking

Estrus (Stage – 2)

The estrus stage is when your dog becomes ready to breed. Typically this stage lasts from 3-21 days. On average, it lasts nine days. This is the stage when your dog is fertile and when her ovaries begin releasing eggs for fertilization.

Symptoms during this period include:

  • Softening of the vulva
  • Lightened discharge
  • Frequent urination
  • Flirting
  • Behavior change

The vulva begins to soften. The discharge is at first very bloody, but with the passage of days, it thins out. A dog in heat often urinates more frequently but in small amounts. She may develop marking behavior. She may urinate on objects (marking) while out walking or even in the house.

During this phase, her urine contains both hormones and pheromones, which is her way of signaling her reproductive status to other dogs. This explains why dogs in heat attract other dogs in the neighborhood, particularly the males. You might also notice your dog moving her tail to the side, making herself accessible to a male dog. Known as “flagging,” this is also a sign that she is fertile and ready to breed. She is simply following her instinct to reproduce.

When she is in heat, your dog gives off pheromones. Male dogs can smell it from some distance away.

Other changes also become noticeable, especially how she behaves. While normally she wouldn’t let male dogs mount her, she is now more than willing. Other females may become aggressive towards her, and she might also return the aggression.

Diestrus (Stage – 3)

During the diestrus stage, your female dog will no longer be interested in mating. The discharge will stop, and her vulva slowly shrinks back to its normal size. Your dog, however, might behave as if she was pregnant, although she isn’t.

Signs of this stage include:

  • The Discharge stops
  • Gradual disappearance of swelling in the vulva
  • Less flirting

The diestrus phase can last between 60and 90 days. At this point, your dog is no longer fertile. In case she has been impregnated, this stage lasts around 60 days. This is from the end of the estrus stage to the birth of her puppies.

If you suspect she might be pregnant, it’s recommended you take her to the vet to confirm whether it is a false or true pregnancy. A false pregnancy can signal a problem.

Anestrus (Stage – 4)

The final stage of the heat cycle is anestrus, the resting stage. The anestrus stage is the longest in a dog’s heat cycle. It can range from 100 to 150 days, after which the entire dog heat cycle starts again.

When should I Breed my dog?

It’s not until the 2nd to 3rd week that she is most likely ready to be bred. The best indication that she can be bred is the reduction of the spotting, a sure sign of ovulation. This ovulation period is the best time for her to visit the breeder. Male dogs will be attracted to your female dog from the first day of her heat cycle, however this does not mean that she is ready.

You will have a greater success of breeding your dog if you allow her to procreate every few days during the period when she will allow a male dog to mount her. If breeding your female dog is not your goal, she must be watched carefully and kept away from any male dogs. Your dog may not be bleeding anymore but can still conceive puppies and male dogs can mount and finish very quickly.

Should I have my dog spayed?

The best way to prevent your dog from going into heat altogether and becoming pregnant is to have her surgically sterilized. Spaying is a surgical procedure that removes the ovaries and uterus. The procedure requires minimal hospitalization for your dog and comes with lifelong health benefits.

For greater detail on what age you should spay a dog see our spay page here. Opens in a new tab.

The timing of a spay operation or ovariohysterectomy varies dependant upon the breed and your veterinarians viewpoint. It was often performed before their first oestrous cycle, but in most instances now, it is performed after the first estrus.

If you have no intention of breeding, to avoid all of the hassles associated with a dog on heat, consider having her spayed when she is still young.  If you cannot watch and protect her during her heat cycles and you don’t want puppies then spaying might be the best option.

What if I choose not to spay my dog?

There are many reasons why people choose not to spay their female dogs. Of course, the biggest reason may be simply to keep her intact for the purposes of reproduction.

If you are planning to show your dog or have her compete in some dog agility competitions, then having her spayed will disqualify her from participating in some shows.

If you decide not to spay, try not to breed her before you have her checked over by the vet ensuring that there are no signs of hip dysplasia. A vet will do a full health check to ensure that she is fit enough to breed. Ideally, the father should also be checked in case he has any genetic diseases. Many puppies are dying at animal shelters every day because some dog owners allow them to breed when they should have been spayed.

If you decide not to spay, ensure you have a suitable and safe home for the puppies. If breeding is your goal, have your vet conduct a few tests during the early stages to determine if she is fit to carry the litter to full term.

If you are unsure what stage of the heat cycle your dog is at a vet can measure blood progesterone levels to determine when she is in heat. This is a simple test done using a small blood sample drawn from the dog and sent to the lab. Low progesterone levels indicate that your dog is not cycling, medium levels that she is in heat while high levels are signs your dog is actually pregnant.

In Season or In Heat Conclusion

A female dog in heat is unintentionally sending out signals in the form of pheromones to all the male dogs nearby. Be prepared. If you own other dogs, it may be a good idea if you separated them at night – for example, consider installing a baby gate.

When walking, always keep her on the lead and preferably walk during the quieter hours of the day to avoid other dogs. Don’t allow her outside unsupervised until the heat season is over.

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