When Do Border Collies Go Into Heat? The Signs And Care Tips

The reproductive stage when a female Border Collie is ready to mate is commonly referred to as being in heat or estrus. 

During the cycle, their body increases in hormonal levels thereafter a sudden decrease which is followed by a readiness to mate and become pregnant, for an unspayed female. 

So, when do Border Collies go into heat? What are the signs? And how do you to care for your female Border Collie?

Read on to learn more on when Border Collies go into heat and all you need to know about the Border Collie’s heat cycle.

When do Border Collies Go Into Heat?: Border Collie First Heat

A Border Collie’s first heat starts between the age of 5 to 8 months of age. This time depends on an individual dog’s body chemistry, genetics, overall health, age, size, and height, however, the majority have their first heat at 8 months of age.

When Do Border Collies Go Into Heat

Understanding The Border Collie Heat Cycle

A Border Collie’s heat cycle is a period that which a female Border Collie goes through a series of hormonal changes which prepare her for reproduction. 

The start of the first heat marks the beginning of reproductive maturity and the cycle repeats every 6 months for the rest of her life.

During a female Border Collie’s heat cycle, they experience four phases as her body changes. These phases are:


This is the start of the heat period of a female and it is where her body starts to prepare to mate. Signs of this stage include:

  • Swollen vulva
  • Blood-tinged vaginal discharge
  • Excessive licking of her genital area 
  • Clingy behavior 
  • Tucking her tail
  • Aggression towards male dogs


The Estrus phase is the main mating phase where a female is in heat meaning they are ready to mate. 

A Border Collie in heat is receptive to males and this occurs when her vaginal discharge decreases. This is when the discharge changes color to a pink/ brownish or straw color.

In this phase she:

  • Urinates frequently leaving marks indicating to males that she is ready to mate
  • Aggressively seeks male dogs
  • Approaches males with her tail on her side (flagged tail)
  • Aggressive to other female dogs


After the Estrus phase, a female dog’s body either returns to normal or develops into pregnancy if she successfully mated.

Her discharge stops completely and her genital areas return to their normal size. Her fertile window has closed at this stage.


This is the last phase of the heat cycle where a female’s body is completely normal and with no signs of sexual behavior or hormonal changes taking place.

It is the period of inactivity where her body gets ready for her next cycle which is again expected in another 6 months.

How long does a Border Collie stay in heat?

A Border Collie stays in heat for 3 weeks. The heat cycle is considered to begin following the first signs of swelling of the vulva, her attention to her vulva, and the appearance of vaginal discharge. The cycle ends when the discharge completely stops and the vulva resumes its usual size.

How Often Do Border Collies Go Into Heat?

Female Border Collies go into heat every 6 months after the first heat. She continues to go into the heat cycle throughout her life.

As a Border Collie owner, it is important to recognize the start of the heat cycle to better care for them as well as prevent breeding.

Signs of a Female Border Collie In Heat

The heat cycle presents changes in a female Border Collie which are observed in various phases of the cycle. When you are trying to identify a Border Collie in heat, look out for the following signs:

Swollen vulva 

One of the first signs of a female Border Collie in heat is the swelling of the vulva. The vulva becomes red and swollen which indicates she has started the heat cycle.

Increased attention to her vulva

Following the swelling of the vulva, a female Border Collie will have an increased interest and attention to her vulva. She will be sniffing and licking it a lot more than usual.

Vaginal bleeding

Blood-spotted vaginal discharge will be produced. Some Border Collies have a heavy discharge while some have minimal discharge. 

To prevent your home from being soiled by the discharge, I recommend getting a dog diaper that they can wear. 

There are washable and disposable diapers available in different sizes which also have an allowance for your dog’s tail. 

Frequent urination

During the heat cycle, a female Border Collie will constantly urinate. This is normal during this time. 

The urine contains pheromones and hormones that give a scent to male dogs signaling that she is in heat and ready to mate.

Behavior change 

When a female Border Collie is in heat, you will notice a change in behavior from her and she will want to mate when the vaginal discharge decreases. 

She will be more distracted and nervous than usual and will try to get pregnant at any cost. 

She will also be more receptive to male Border Collies by courting them, initiating the mating position by raising her behind towards them or moving her tail on one side which is known as “flagging”, to enable mating. 

To prevent breeding during this time, walk her on a leash when outside your home where she may meet male suitors, and also keep her contained in your house or backyard to prevent access to male dogs. 

A Border Collie in heat will also have clingy behavior towards its owners. 

This behavior change is temporary and she returns to her normal self after her heat cycle ends.

See Also: Why is my Border Collie so clingy?

How to care for a Border Collie In Heat

If your Border Collie is going through her heat cycle, it is best to be well prepared on how to care for her to keep her comfortable. 

The following are the different ways you can do this:

Allow her to have extra rest during her cycle. A female Border Collie needs energy as she goes through the motions of the whole cycle. 

Therefore allow her to have enough rest by easing her activities such as her exercise routine by taking shorter walks. 

Do not let her off her leash during walks to prevent her from running off to a male dog that she may encounter.

Keep your dog comfortable by keeping her environment calm and away from noise or other triggers of stress.

This helps to keep her calm, happy and it also distracts her from the discomfort of her hormonal changes

Keep her from your furniture or carpeted areas during the bleeding phase to prevent her from creating a mess on the surfaces. Dog diapers are essential during this time. 

If she needs to lick herself while in a diaper, remove it temporarily to allow this natural process.

Feed her well with plenty of drinking water to keep her healthy and to have energy from her food sources.

Isolate her in your home or backyard away from male dogs. Supervisor her when in the backyard because she will have the drive to look for a mate and might try to escape to achieve this.

Consult with your veterinarian if you notice any signs of illness. Female Border Collies may develop a bacterial infection from the remains of their thickened uterus after their cycle. 

This uterine infection also known as pyometra is life-threatening therefore ensure to observe your dog for signs of illness which include:

  • Excessive drinking of water
  • Excessive urination 
  • Loss of appetite
  • Production of thick discharge from her genitals
  • Abdominal pain
  • Weakness

After her heat cycle plan to have her spayed. If your intent is not to breed your dog, this is the next step to consider so that she will not reproduce. 

At what age should a Border Collie be spayed?

A female Border Collie should be spayed when they are at least one year old and after they have experienced their first heat cycle. Having them spayed at this time prevents the occurrence of developmental issues and also prevents the formation of blood clots due to an increase in hormone levels during and around the heat cycle. 

Therefore they should also be spayed when they are one year old and at least two months after their heat cycle.

Key Takeaway

When a female Border Collie matures sexually, they go through a cycle where they are ready for mating which is commonly known as being in heat.

This is a stage you will notice both behavioral and physical changes that will confirm they are in a heat cycle.

As a Border Collie owner, being aware of these signs helps you to be more prepared in terms of their care as well as prevent breeding.

Also, talk to your veterinarian about spaying your female Border Collie and  neutering your Border Collie male dog. 

I hope this article gave you an insight into when Border Collies go in heat and what you can do to care for them during their cycle.