Understanding your dog's seasons

Dog, resting

If you own a bitch (female dog) that hasn’t been neutered, it’s important to understand when your dog is likely to have her first season, how often they happen, what to expect and symptoms to keep an eye out for that she’s in heat.

What is a season?

A dog’s season, otherwise known as being ‘in heat’, is the part of a female’s reproductive cycle that can allow her to become pregnant. When she’s in season, your dog may act differently and her genitals may swell and produce a discharge. Knowing how to recognise the signs of heat, and being able to roughly predict when a dog’s in season, can help owners avoid unwanted pregnancies and allow breeders to know when their dog is fertile.

Your dog’s first season

Your dog’s breed and size play a big part in when she is likely to have her first season. Most smaller breeds can have their first season at around six months old, but this can vary quite a lot from dog to dog, while some larger breeds may not go in to heat until they are over a year old. Having her first season is a sign that she’s now sexually mature and is physically able to have puppies. For some dogs, it’s obvious that they’re having a season, while for others, the signs may be more subtle.

How often do dogs come into season?

After your dog’s had her first season, she is likely to continue to have regular seasons, usually every six to seven months. How regular your dog’s seasons are can depend on her size and breed. Younger dogs may have irregular seasons to start with, but these usually settle down and become more consistent within a few seasons. Your dog’s seasons can be affected by being in the company of other females that are in season.

At what age does a dog stop having seasons?

Dogs don’t go through the menopause like humans do. Instead, they carry-on having seasons throughout their life. This means that they’re able to get pregnant at any age. We will not usually register a litter to a dam over the age of eight, and most responsible breeders won’t breed from a dog once they are at this age because of an increased risk of complications during pregnancy and birth. As your dog gets older, the length of time between their seasons can get longer. This is nothing to worry about and is just part of the aging process.

How long is a season?

Dogs are usually in season for about three weeks, but this may be as short as two weeks or as long as four.

Signs your dog is coming into season

Some dogs may have very obvious physical signs that they are in heat, while others may be more subtle.

Signs your dog is in season may include:

  • Their vulva (the outer parts of their genitals) becoming swollen and red. Some dogs may be more noticeable than others. This change usually happens a few days before they begin to bleed
  • A vaginal discharge that can start off bloody but may become watery and more pinkish as their season progresses. For some dogs, the discharge may be more yellow in colour or can be brown
  • Cleaning their genitals more than usual by licking them
  • Weeing more often

Some females may bleed heavily, and this may be normal for your dog, but if you are concerned then always speak to your vet for advice.

Common behaviours of dogs in season

As your dog comes into season, and certain hormones begin to increase, you may notice her behaving differently. This might include:

  • Being more friendly to other dogs, particularly males
  • Going out of her way to look for potential mates. When in season, and especially as she becomes more fertile, she may be less inclined to return to you when called
  • Mounting other dogs, pets, furniture, toys or you
  • Moving her tail to one side when touched or when around male dogs
  • Being anxious, clingy, fidgety or nervous
  • Nesting or gathering toys where she sleeps
  • Being off her food
  • Being more domineering
  • Marking her territory with urine
  • Being defensive of other dogs going near her rear end

Your dog’s behaviour may change throughout her season, for example she may be defensive of dogs sniffing her at the beginning or at the end of her season, but may be keen to let them investigate her when she is most fertile. All of these behaviours are natural and nothing to be concerned about and should disappear once she’s finished her season.

How long does a dog in heat bleed?

Most dog’s bleed for roughly seven to 10 days (around half of their cycle). Your dog bleeding is a sign that their body is undergoing changes that help her to become fertile.

How much does a dog in season bleed?

Some dogs may bleed heavily, while for others it may be barely noticeable. Although some dogs may have a very obvious bloody discharge, it may be less noticeable depending on how much they groom and clean themselves.

Do dogs get ‘period’ cramps?

It’s difficult to tell. Without dogs being able to tell us how they feel, it’s hard to know what your dog is going through, but we suspect that it’s generally not painful. Some dogs do seem to be uncomfortable during their season and may be a little fidgety, but it’s unusual for there to be any obvious signs of pain.

Do female dogs hump when they come into season?

Yes. A surge in hormones may cause your dog to want to mate and is a common sign of a female in heat. She may try to mount or thrust on other dogs (male or female), other pets, toys, furniture, cushions or even you (especially legs).

Do dogs pee more when in season?

When your dog is in season, she may pee more often and may use her urine to scent mark when out for a walk, in the garden or even around the house. When in heat, your dog’s urine contains hormones and pheromones that tell other dogs that she’s fertile. Male dogs can smell these hormones and may try to visit her, or may urinate near your house in an attempt to stake their claim.

How to take care for a dog when she’s in heat

During her season, your dog may seem uncomfortable, anxious and a little confused about the changes that are occurring to her body. All dogs are different and some dogs may need more comforting than others. To help your dog you could:

  • Keep her distracted with games and play these around the house
  • Take her for regular exercise (away from male dogs who may show an interest in her)
  • Give her a treat filled toy – remember to count these as part of her daily calorie intake

How can I keep my house clean with a dog in heat?

Each dog is different, some dogs may not bleed a lot, and others may be meticulously clean and lick themselves to get rid of any discharge. However, if you’re concerned about your dog making a mess when in season then you could limit her access to sofas, bedding and carpeted areas. Some people put down plenty of towels in areas that their dog usually sits and others use special pants that help to catch the blood.

Can you get ‘period pants’ for dogs in season?

Yes. If your dog tends to bleed heavily during her season, then you can buy pants specifically designed for dogs that stop them bleeding on the floor and furniture. Some dogs may not find them comfortable, so try getting your dog used to them before they’re in season. Remember that although these pants may do a good job of keeping your house clean, they may not be effective at preventing her from attracting a mate or successfully mating.

Should I walk a dog in season?

During her season, your dog will be very interesting and attractive to males, and the feeling may be mutual, especially when she’s ovulating. To prevent any unwanted interest, or accidental matings, it may be best to walk your dog at quieter times of the day and stick to quieter areas where you know not many people walk their dog. During this time, always keep your dog on the lead to stop her from running off to a potential mate. Keep her close by in case any interested males do come too close. If possible, you could give them exercise and stimulation at home or in your garden.

Complications of dogs’ seasons

After a dog’s season, some dogs may show signs of a false pregnancy. This is a condition that causes them to act as if they were pregnant when they’re actually not, with them producing milk and even gathering objects into a nest as if they were puppies.

False pregnancy is caused by a change in hormones and is common in unneutered dogs. Many dogs will experience these effects and recover from them naturally, but they can be stressful and can lead to more serious complications, such as pyometra. Pyometra is accumulation of pus in the uterus (womb), which can be life threatening.

Signs of 'pyometra can include:

  • Being off her food
  • Seeming tired
  • Being sick
  • Drinking more
  • Licking her genitals
  • Having a smelly vaginal discharge.

If you notice any changes in the patterns of your dog’s season, especially if they appear to remain in season for an unusually long time, you should talk to your vet.

Dogs seasons and mating - when to mate your dog

All responsible breeders recommend waiting until your dog is physically and mentally mature before mating them. This usually means letting them have several seasons before breeding.

Female dogs are only fertile when they’re in heat. Once she’s in season, the time that your dog releases her eggs and becomes keen to mate, usually coincides with her discharge becoming watery. You could use this as a sign to mate your dog, but some dogs may not have very noticeable discharge and using this method is not very reliable. There are two tests that your vet can perform that are more accurate. These include a vaginal smear test and a blood test that checks progesterone levels.

Understanding the stages of your dog’s season

During a dog’s reproductive cycle, changes in her hormone levels cause her to behave differently and for her genitals to undergo a change, all to increase the ability of her becoming pregnant.

There are four main stages to a dog’s reproductive cycle and these are:

  • Proestrus: A dog’s oestrogen levels start to rise in preparation for her to release her ova (eggs). Her vulva may swell and she may produce a bloody discharge. Although male dogs may begin to take an interest in her, she may not be keen to mate, and may not be happy about dogs sniffing around her. This stage usually lasts for around nine days, but varies from dog to dog.
  • Oestrus: As her oestrogen levels drop, her progesterone levels begin to increase. This is the time when your dog is most fertile. She will have released her eggs and will allow herself to be mated. Her vulva will still be swollen and her discharge will be less bloody and may now be pink or straw coloured. She may present herself to males and may move her tail out of the way to encourage males to mate. This stage usually lasts just a few days.
  • Diestrus: During this stage, your dog will no longer be fertile, but she will still be producing progesterone to help if she’s pregnant. During this time, her vulva will become less swollen and she will show less interest in mating and in males. If she’s not pregnant, high levels of progesterone can cause phantom pregnancies.
  • Anoestrus: This is the time when her hormone levels return to normal and is the period before her next heat cycle begins.

How long after bleeding is a dog fertile?

In humans, a woman’s period is a sign that she’s finished ovulating, but in dogs it’s actually a sign that they are about to become more fertile. Dog’s may start with a very bloody discharge, but this changes and become watery over time. This can indicate that she is at her most fertile and this stage can last for around 10 days, but varies from dog to dog and may be breed dependant.

What if my dog mates during her season?

If your dog mates during her season, and it was not an intentional mating, then speak to your vet as soon as possible. There are certain injections that can be used within the first few days after mating that can prevent pregnancy. Your vet will be able to give you advice about your options and can discuss any risks involved.

How to prevent pregnancy when in season

During your dog’s season, she will become very attractive to males and may be keen on mating with them. To prevent your dog from becoming pregnant, it’s important that you keep her away from male dogs. To do this you could:

  • Walk her on a lead at quieter times of the day, or in places where there are fewer dogs
  • Avoid taking her around to other people’s houses who have unneutered males, or to any socialisation classes
  • Avoid leaving her alone in the garden. Some males may be able to smell that she is in heat and may try to get into your garden to mate with her
  • If you have any unneutered male dogs in the house, and do not want them to mate, then you may need to keep them separated

Can a dog get pregnant when not in heat?

No. Your dog can only get pregnant when they’re in season, but most bitches will only mate when they’re in season. If your dog has let herself be mated, then it could be that she’s in heat. This is the time that their body becomes most fertile and releases an egg, ready for fertilisation. They are most fertile for several days in the middle of their heat cycle. But it’s still possible that, due to sperm usually being viable for several days (or even up to two weeks) after mating, if they are mated before their most fertile period, they can still become pregnant.

Not breeding from your dog? Have you considered neutering?

If you’re not thinking of mating your dog, then you may want to consider investigating whether to have them neutered. Neutering is a common operation that’s performed on over half of dogs in the UK. It stops your dog from getting pregnant and means that they don’t have seasons anymore. Neutering can also reduce certain behaviours and lowers the risk of certain health issues.

Find out more about neutering.

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We are not a veterinary organisation and so we can't give veterinary advice, but if you're worried about any of the issues raised in this article, please contact your local vet practice for further information