Dog in Heat : Cycle and Mating Process

A little knowledge about the dog heat cycle and dog mating process might prepare you for the experience especially for first time dog owners. Whether your dog is male or female, knowing the female dog in heat symptoms will help you to prevent unwanted pregnancies as well as dangerous or unpredictable situations. Read on to discover more about the stages of the dog heat cycle as well as the dog mating process. 

Cycle and mating process
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Dog heat cycle stages

There are 4 stages to the heat cycles in dogs.

Proestrus stage

This is the first stage of the dog heat cycle and can last from 3 to 17 days, with most dogs averaging 9 days. During this stage, you may notice symptoms such as:

  • Appetite changes - Your dog may seem hungrier than usual, or may be eating less. Whichever the case, it's a good clue that the Proestrus stage has started. 
  • Personality changes - Just like humans, your dog may be rather grumpy during this time. She may also be more affectionate and clingy to you. 
  • Swelling of the vulva - This is a good way to tell that your dog is in the first stage of the heat cycle. Light bleeding usually occurs during the first few days and gets heavier after that. 
  • Tail tucking - Your dog may tuck her tail between her legs or sit down when another dog is nearby. She does this to protect her vulva. 

Estrus Stage

The Estrus stage is the second part of your dog’s heat cycle. This stage can last for 3 to 21 days and similar to the Proestrus stage, an average of 9 days. 

It is during this time that your dog’s ovaries release eggs for fertilization. Your female dog may look for some male company by wanting to go outside more often. Besides this, you may also notice the following: 

  • Softening of the vulva - The swelling during the Proestrus stage subsides to ready so that the vulva is soft enough for penetration.
  • Lightened discharge - The red discharge now lightens to a pinkish color
  • Flirtatious behavior - Instead of tucking her tail your dog may try to get male attention by turning her rear towards him as well as holding her tail high. 

Diestrus Stage

Once the fertile period of the Estrus stage comes to an end, it is called the diestrus stage. Your dog is no longer fertile at this point. This stage lasts until your dog gives birth to puppies if she has been impregnated, which will be in 60 to 90 days. During the Diestrus stage, you will notice:

  • Swelling of vulva gradually disappearing - Although the vulva may still be a little enlarged, most of the swelling usually settles within a week. 
  • Less flirting - Your dog is not longer interested in mating 

Anestrus Stage

The final stage of the dog heat cycle is also known as the resting stage. This period lasts for 100 to 150 days. The heat cycle starts over at the end of Anestrus stage. 

Dog mating process 

The dog mating process can be divided into three parts. 

First stage coitus

First stage coitus takes approximately 2 minutes. The male dog will sit on the female dog. As dogs will not be able to stay in this position for long due to severe cramps that will occur, they will change position.

The turn

The turn to change position takes about 5 seconds. The males dog achieves this by swinging one of its hind legs over the female dog’s body. 

Second stage coitus

Second stage coitues can be anywhere from 5 to 45 minutes. The male and female dog will be standing rear to rear during this stage. Part of the male dog’s penis swells and enlarges while the female dog’s vaginal muscles contract against the male dog’s penis. This ‘tie’ prevents the penis from being withdrawn. 

Can I separate dogs while they are mating? 

You should never forcefully separate dogs during the mating act. As the female dog’s muscles are contracted and the male dog’s penis is swelling, it will not only upset the dogs but also cause serious harm to them. 

While it can be rather embarrassing for onlooking humans, the mating act between the dogs is a normal dog behavior.

Can you spay a dog in heat? 

Dogs can be spayed when they are in heat but this might cause bleeding and other surgical complications. As such, most vets prefer to wait until the resting stage to avoid complications. 

The best age to spay your female dog would be at around 6 months. Male dogs are usually neutered when they are between 5 to 10 months. Your vet will know the best age for surgery for your dog, depending on its breed and size. 

the puppies
Photo by Anoir Chafik on Unsplash


Knowing when your dog is in heat will not only prevent unwanted puppies but also help you to plan for puppies if you want them. If you don’t plan on being a grandparent to your dog’s pups, it’s best to spay or neuter your dog before its first heat cycle. As always, do consult your vet if you have any questions or concerns with your dog’s heat cycle.