Pet ownership comes with its ups and downs as they cycle through the stages of life. For female dogs, this includes going into heat. A female dog’s heat cycle – also called her oestrus cycle – is a normal biological process. It’s helpful to understand how it all works, so you know exactly what to expect and how to best care for your pet during this time. In this article, we’ll walk through everything you need to know about your dog’s ‘season’, from first heat through to behavioural changes.

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What is a dog’s season?

A dog’s season, also known as ‘being in heat’, refers to the recurring timeframe when a female dog can become pregnant. This reproductive cycle occurs about twice a year beginning around 6 months of age. Triggered by the release of reproductive hormones, the heat cycle generally lasts for about 21 days. However, this duration can vary significantly between individual dogs and breeds.

When does a female dog have her first heat cycle?

Most female dogs will experience their first heat cycle between 6 and 15 months of age. Smaller breeds tend to sexually mature and go into heat earlier, while larger breeds start their cycles later. If you are worried about the timing of your dog’s first oestrous cycle, it’s a good idea to consult your vet for advice.

How long are dogs in season for?

The average heat cycle for a dog lasts about 21 days, or 3 weeks. However, every dog is individual, so this can range from 2 to 4 weeks. Your dog’s reproductive cycle begins with about a week of vaginal bleeding and/or discharge. This is followed by about a week of peak fertility when the dog can get pregnant most easily. The cycle ends with roughly a week when fertility tapers off again. So, the total cycle may last 2 to 4 weeks, but the fertile window when mating could lead to pregnancy is usually only about 1 week.

The four stages of a dog’s heat cycle

A dog’s season follows a cycle with four distinct stages:

Proestrus – This initial stage marks the start of a dog’s heat, lasting about 7-10 days. 

Oestrus – This is the most fertile phase, typically lasting 5-10 days. 

Metoestrus – With discharge changing from bloody to watery, this phase lasts about 55 days as the dog’s body prepares for potential pregnancy after breeding. 

Anoestrus – This sexually inactive resting phase lasts 4-5 months until the next heat cycle begins. 

You can read more about these stages here.

How often does a dog come into season?

Most dogs experience heat cycles approximately twice yearly, or about every 6-8 months. But this can range anywhere from 3-4 times a year to only once annually. Smaller breeds tend to cycle more frequently than larger breeds. Factors like the dog’s health, breed, climate, and day length can impact the dog’s cycle and frequency of ovulation.

What signs indicate that my dog is in heat?

There are some classic signs to watch out for when your dog is in heat:

  • Swollen vulva and bloody or straw-coloured vaginal discharge
  • Increased urination and excessive licking of the genital area
  • Behaviour changes like nervousness, irritability, and restlessness
  • Strong attraction of male dogs who may roam or try to escape confinement
  • Standing still while males attempt to mount – the standing heat posture

Keep females safely away from all male dogs during her cycle to prevent unwanted mating and resulting pregnancy.

Puppy’s first season

Puppies usually experience their first heat cycle somewhere between 6-15 months of age. Small breeds can enter heat as early as 4 months, while some larger breeds may not experience their first oestrous cycle until 12-18 months old.

Expect the unexpected during this time – the changes don’t always follow the usual pattern. In fact, puppies going through their first season of heat often have irregular cycles. It’s important to closely monitor your puppy as she enters her first season. Call your vet straight away if anything seems unusual or concerning.

Can a mature female dog not go into heat?

Most unspayed female dogs will go into heat at some point. If your dog reaches maturity without showing any signs of heat, this is considered abnormal. Some possible reasons for a lack of heat cycles include:

  • Hormonal problems or irregularities inhibiting ovulation
  • Undiagnosed health conditions impacting the reproductive tract
  • A genetic abnormality affecting hormone regulation or release
  • Physical issues like obesity impairing reproductive function

If your adult dog reaches two years of age without experiencing her first season, it’s a good idea to consult your vet. They’ll be able to test for any underlying medical causes.

How long do dogs bleed when in heat?

The amount of time a dog spends actively bleeding can vary. Some dogs may only bleed for 4-5 days, while others can bleed for up to 13 days or more. The volume of blood loss also varies greatly, from barely noticeable spotting to heavier discharge. Monitor your dog’s unique bleeding patterns to determine what’s normal for her cycles.

Do male dogs go into heat or season?

No, male dogs do not go into heat the way females do. They are capable of mating and impregnating a female dog at any time after reaching sexual maturity. This means they can mate year-round. However, certain factors can impact fertility and sex drive in males as well, including health status, diet, obesity, and age. 

Do female dogs go into heat throughout their lives?

Yes, female dogs go into heat well into their old age. Dogs don’t go through menopause like humans experience it, which means they can continue to get pregnant throughout their lives. If your mature female dog abruptly stops cycling, consult your vet to rule out any underlying health issues causing this change.

Can dogs be aggressive in heat?

It’s often reported that female dogs display some aggressive behaviours when they are in season. This is probably due to hormonal fluctuations that can cause irritability, restlessness, and mood swings.

However, true aggression is relatively rare. While pet owners often describe their dogs being anxious, clingy, or short-tempered, this doesn’t necessarily equal aggression. 

If aggressive behaviour does arise, never punish your dog as this can make it worse. Instead, manage the situation by:

  • Keeping the dog safely and comfortably confined when unattended
  • Avoid interaction with children
  • Briefly separating from other pets if needed
  • Keeping the dog on its lead, avoiding triggers on walks
  • Speak to your vet about calming aids and practices

Significant aggression is not typical of dogs in heat. But if concerning behaviours persist, or the aggression is extreme, always consult your vet. Aggression should always be addressed professionally rather than attempting to manage it without help. With proper treatment, you’ll keep your dog more comfortable – and even-tempered – throughout her heat cycles.

What is pyometra and why is it associated with dogs in season?

Pyometra is a bacterial infection of the uterus that most commonly affects female dogs who have not been spayed. It’s usually seen in middle-aged to older dogs; but can occur at any age. It often happens a few weeks after a dog has finished her season.

Pyometra develops when bacteria enter the uterus and cause an infection. This leads to a buildup of pus and fluid that distends or enlarges the uterus. Without treatment, the infection can spread systemically and even become life-threatening.

Symptoms of a pyometra infection often include:

  • Lethargy, depression, loss of appetite
  • Vaginal discharge that may be bloody or mucus-like
  • Increased thirst and urination
  • Fever
  • Enlarged or painful abdomen
  • Vomiting, diarrhoea, or sepsis in advanced cases

Pyometra is a serious medical condition that requires prompt veterinary treatment.

The benefits of spaying your dog

Due to the risks posed by unwanted mating and pregnancies, most vets strongly advise pet owners to have their female dogs spayed either before their first heat cycle or very shortly after. However, spaying before physical maturity can cause other problems, and the exact best time to spay should always be a decision made with your vet for that particular dog as an individual. 

Spaying is an abdominal surgery to completely remove the dog’s ovaries and, often, uterus. It prevents pregnancy and permanently stops heat cycles. Spaying offers a wide range of health benefits and is widely recommended by vets and animal welfare groups for population control purposes as well. Discuss the ideal timing for this procedure with your vet. 

Five things to do when your dog is in season:

Be aware of dogs in season behaviour changes

When your dog enters her heat cycle, you may observe some changes in her behaviour:

  • Increased nervousness, restlessness, agitation, or irritability
  • More vocalisation like whining, crying, or barking
  • Loss of appetite and less interest in toys, play or walks
  • Mounting people, objects, and other dogs, sometimes humping excessively
  • Licking or chewing at genitals obsessively
  • Urinating more frequently and having indoor accidents
  • Attempts to escape or roam free in order to find a mate
  • Not listening to commands, difficulty concentrating or paying attention

These behavioural changes are all related to the hormonal fluctuations during a dog’s cycle. Be patient with your own dog in season and avoid scolding during this time. Keep your dog’s bed or crate area clean, and teach children how to interact safely with a dog in heat.

Taking dogs out during their heat

Special care should be taken when walking a dog in season. While exercise is still important, there are a few risks to consider.

The powerful scent of a female in heat can attract male dogs from far distances. Roaming males may pick up her scent and come running, attempting to mate. This can make regular walking extremely difficult.

To stay safe, it’s best to limit walks to a secure area. Keep your dog on a lead for control. Only take her out alone rather than with other dogs, keeping alert for approaching males. Avoid all public areas like dog parks, trails, pet stores, etc.

Indoor exercise can be provided instead through play, training, puzzle toys and calming activities. If you must walk your dog in heat, do so during very low traffic times. Choose routes and times where few dogs are around.

While exercise is important, safety must come first. With planning and proper precautions, you can ensure your dog gets enrichment without undue risk during her heat cycle. Her regular walking schedule can resume once the heat has ended.

Caring for your dog during her heat cycle

To help keep your dog comfortable and your home clean during her heat, follow these tips:

  • Provide your dog with a quiet private space away from other pets
  • Stick to a calm, consistent routine to reduce behavioural stress
  • Monitor for any symptoms requiring vet attention and respond promptly

Managing household cleanliness

One challenge of a dog in heat is managing the bloody discharge that occurs inside your home. Be prepared with:

  1. Washable pet beds, blankets, and furniture covers
  2. Easy-to-clean flooring like tile, wood, or vinyl
  3. An effective pet stain remover and carpet cleaner
  4. Dog nappies or period pants are available but don’t suit all dogs. Speak to your vet first if you’re considering this.

While it requires a little extra effort, maintaining a clean home during a heat cycle is easily manageable for most dog owners.

Consult your vet with any concerns

If your dog’s heat cycle or behaviour doesn’t seem right, contact your vet straight away. Symptoms like irregular or lengthy cycles can indicate an underlying health issue needing treatment. Your veterinarian can also advise you on optimal preventive care to keep your dog comfortable during her many seasons throughout life. With the right knowledge and preparation, you’ll be able to keep your dog safe, healthy, and happy.

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