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Dog Heat Cycle Calculator

Created by Aleksandra Zając, MD
Reviewed by Łucja Zaborowska, MD, PhD candidate and Adena Benn
Last updated: Jan 18, 2024

If you want to know when your female dog will come into season again, the dog heat cycle calculator is the place to learn! Read on and:

  • Learn the signs of a dog heat cycle other than bleeding;
  • Get to know when a dog can get pregnant; and
  • Learn how to avoid heat cycles - medication to stop the cycle and spay.

Female dog heat cycle chart & overview

Bitches usually mature and start their first heat cycle when they are six months old. However, it's very individual and can vary from dog to dog. It also depends on the dog's size. Miniature breeds tend to grow faster. Female dogs of the chihuahua or pomeranian breeds can have their first cycle at four months. On the other hand, giant dogs like the great danes can reach as much as two years before their first heat.

A typical, visible heat cycle lasts for 2-3 weeks - it's the moment when a dog can get pregnant. Bitches are not necessarily fertile throughout the whole heat, but sperm can live in a dog's birth canal for days. If you don't want puppies, stay on the safe side and keep your pup from her admirers for the whole heat. If you're hoping for pups, you can check the dog due date in one of our calculators.

An image showing dog heat cycle.

Take a look at the dog heat cycle chart above. The part we refer to when saying 'heat' is the proestrus and estrus.

  • Proestrus is when typical bleeding occurs. At this point, a pup is getting ready for mating, but she won't accept a male dog as yet.
  • Estrus - is when ovulation happens; a female dog is likely to mate and become pregnant.
  • Metestrus/diestrus - she's no longer fertile, this phase lasts for 60-90 days (2-3 months).
  • Anestrus - lasting 90-150 days (3-5 months). Bitch is no longer fertile. She shouldn't present with vaginal discharge or swollen vulva.

How often will that happen? Unless you spay your dog or use medication to stop the dog heat cycle, heat will happen every six months. This might also vary; again, we've got a breed-dependent pattern. Small dogs will experience heat more often, even every four months. Giant breeds, on the other hand, are in heat less often - e.g., only once a year.

How to use the dog heat cycle calculator?

To use our dog heat cycle calculator, you only need to enter the first day of the last female dog cycle. If you keep track of your dog's heat cycle and know her cycle's length, you can also enter it.

The calculator will give you:

  • The predicted duration of this cycle;
  • A predicted range of dates when the next heat cycle should happen.

Keep in mind that dogs' hormonal cycles vary a lot between breeds and also between individual dogs. Observing your dog and keeping close notes is the best, most accurate way to predict a cycle. However, even this method has its drawbacks - if your pup is young, her cycles might be irregular.

Signs of a dog's season - not only bleeding

If you would like to keep track of your dog's heat cycle but do not know what to look for, here are some indicators that can help you to identify this period:

  1. Swelling of the vulva (this might not be obvious, especially if you're not an experienced dog owner).
  2. Female dogs will lick themselves more often.
  3. Vaginal discharge - bleeding.
  4. Mood changes - a dog can get more clingy or, on the other hand, needs more space or become grumpy.
  5. Appetite change - a bitch can refuse to eat her usual dog food or become hungrier.
  6. Tail tucking at the beginning - usually becomes tail flagging when a bitch reaches the estrus state.
  7. Flirting with other dogs.

Using the dog heat cycle calculator, you can treat the dog on the day the signs start - the first day of the cycle.


Is there a medication to stop the dog heat cycle?

We can use two medications to stop a dog's heat cycle:

  1. Megestrol acetate - this stops the current cycle.
  2. Mibolerone - this should be given to a dog ~ a month before the next season; as an effect, it will prevent the heat cycle.

You should consult a veterinarian before using any of these drugs. You should not use these drugs as a lifetime way of preventing your dog from getting pregnant. If you don't plan to breed your dog, consider a spay.

When is the first dog's heat cycle?

The approximate age for a female dog's first heat cycle is six months old. However, it varies a lot - individually and from breed to breed. Small breeds usually mature faster - while about four months old. Some giant breeds will get their first cycle at two years old.
Young dogs also tend to have irregular cycles, so don't expect everything on time in the first few bitch cycles.

Can a female dog be spayed during her heat cycle?

Yes, it is possible to spay a cycling dog. However, it has a greater risk of complications than spaying a dog between cycles. The decision will be individual to every situation, and your vet has the final word.

When is my dog's next heat cycle?

To know the date of the next heat cycle:

  1. Get the date of the last heat cycle and add ~ 5-8 months.
  2. Your dog should come into season within that range.
  3. You can check your results in our dog heat cycle calculator.

However, some small breeds can go into heat once every four months, whereas giant breeds tend to have rare cycles - e.g., once a year.

The most accurate way to predict the heat cycle in an individual dog is to observe her and her cycles closely.

Aleksandra Zając, MD
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