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How Do I Know If My Dog Is "in Season"?

Sophie Jackson is a dog lover and trainer living in the UK. She competes in agility and obedience with her four dogs.

Only when a dog has a season can she become pregnant. Do you know the signs of a season?

Only when a dog has a season can she become pregnant. Do you know the signs of a season?

What Is a Season?

Unlike humans, dogs are only able to become pregnant at certain times when their body is receptive to the reproductive process. This is known as a season or heat cycle. It lasts 2-3 weeks and during this period a female dog becomes very attractive to male dogs and can become pregnant if she is mated.

A female dog's body goes through a number of changes as she comes into season, and these prepare her for accepting a male and becoming pregnant. There are behavioral changes as well as physical changes that will be noticeable to the owner. These will disappear a few weeks after the season is finished.

Female dogs can experience their first season as young as 6 months of age, or as old as 2.5 years. In their first season, most dogs are not physically mature, so mating should never be considered. It is important to keep your dog safe at this time to prevent males from mating with her.

After her first season, most female dogs will experience one every six months, though some dogs will go longer. Certain breeds are known for having longer times between seasons. Basenjis, for instance, only come into season once a year.

When a dog is in season, she may become extra playful with male dogs.

When a dog is in season, she may become extra playful with male dogs.

Stages of a Season

There are four stages of a season and only during one of them is a female dog interested in mating.

Stage 1: Proestrus

This is the beginning of a season, but not the point when a female dog is ready to mate. She may show behavioral changes due to the hormonal fluctuations occurring in her body, and male dogs will start to pay attention to her, but she will not be interested in them. She may act protectively of herself. The dog's vulva (her female genitals) will swell and there will be some bleeding. This stage usually lasts 9 days but can last up to 27 days in unusual cases.

Stage 2: Estrus

It is during stage 2 that female dogs welcome male attention and are most fertile. The swelling of the vulva may decrease a little and bleeding can ease or even stop - some owners believe their dog is now out of season, when in fact she is at her prime time to become pregnant. This stage lasts between 4 and 24 days, but on average lasts 9 days. To avoid unwanted pregnancy, it is very important to keep your dog away from males at this stage.

Stage 3: Diestrus

This is the stage after a season when a female's body is recovering from the hormone changes. When choosing to spay a female dog, vets recommend waiting until she has come through the diestrus stage, which lasts about 2 months. It is also at this point a dog can suffer a phantom pregnancy. Females will no longer be interested in males, though there may be some lingering unwanted attention for the first couple of weeks after estrus. Any physical and behavioral changes should gradually resolve.

Stage 4: Anestrus

This is the stage between seasons when your dog is just herself and her hormones have settled down. It lasts around four months (in certain breeds it's considerably longer) before proestrus begins again.

Dogs may experience behavioral as well as physical changes during a season.

Dogs may experience behavioral as well as physical changes during a season.

Signs of a Season

As there are several stages to a season, there are also several signs of it occurring. Some are more obvious than others and not all dogs display the full range of symptoms. If you have a female dog, especially a puppy, it is important to watch for signs as she reaches 6 months of her first season. After this, expect to see similar signs every 6 months throughout her life, or until she is spayed.

Physical Symptoms

  • Swollen vulva: This is your dog's genitalia, but also where she urinates from. It usually becomes noticeably enlarged during a season, but might be harder to see on a long-haired dog.
  • Bleeding: Many female dogs are very clean during their season and you will see few signs of bleeding. You may notice spots of blood where your dog has been sitting or resting, these will be bright red at the start of the season, then fade to a straw-colored discharge, before becoming pink again. Most people think it is when a dog is bleeding she is ready to mate, when in fact it is when the bleeding turns pale or stops that she is receptive to males.
  • Swollen nipples: The nipples swell in expectation of pregnancy and puppies needing to feed on them. In some cases, it can take several weeks for the nipples to return to normal after a season.
  • Increased urination: Your dog may begin to urinate more often during her season, she may also begin to mark (where she does lots of small pees as she is being walked). The urine is full of hormones and pheromones that tell a male dog she is in season and by marking a female dog is advertising herself to them.
  • Showing discomfort: It is difficult to know if dogs having a season feel aches and pains as humans do when having a period. Vets are of the general opinion they do not, but some dogs in season do appear to show signs of discomfort and pain.

Behavioral Symptoms

Behavioral changes are often the first indication a female dog is coming into season. Some dogs exhibit more of these signs than others.

  • Becoming clingy: One of the first things a lot of owners notice is that their dog starts to hover around them often, doesn't want to let them out of her sight, and tries to get as close to them as she can. She may seem very needy and desperate for attention.
  • Becoming aloof: In contrast, some dogs become aloof at this time and may choose to spend time away from their owners, in another room of the house, or just keep to themselves. They may show little interest in engaging with the owner in games or training.
  • Grumpiness: Some female dogs become moody; they may be snappy or growl unexpectedly. They may start to guard bedding, food, or toys, or become resentful of being moved from the furniture. They may also be aggressive to other dogs they meet, especially males when they are not yet in estrus and ready for them.
  • Nesting: Some females will start to prepare a 'den' for their pups, even if they have not been mated. They may collect toys as surrogate puppies and place them in this den. Nesting can be an early warning sign of a phantom pregnancy, which is a complication of a season.
Dogs 'tie' when they mate. If this happens to your dog when she is in season, it is very possible she will become pregnant.

Dogs 'tie' when they mate. If this happens to your dog when she is in season, it is very possible she will become pregnant.

What Should I Do While my Dog Is in Season?

A season is a natural event and most dogs will cope well with it. Some may seem off-color, turning down their food or sleeping more. If these symptoms are associated with other signs, such as an upset stomach, you should consult your vet in case there is something else wrong. Equally, if these symptoms last longer than a week or two, you should speak to your vet.

Otherwise, the most important thing is to keep your dog safe from unwanted attention from male dogs. You should not walk her in dog parks or areas where lots of dogs are exercised, even if you keep her on lead. Male dogs will be attracted to her and will pester her. This can cause some females distress.

When your dog is at the peak of her season, she will be receptive to male dogs and will allow them to mount her. This can happen in seconds and once it occurs, the dogs 'tie'. This is a process where the dogs become temporarily joined together and cannot be separated as the male dog's penis swells to lodge in the female. It is important you do not force the dogs to separate at this stage, as you can cause severe damage to both of them.

Once the dogs have tied it is too late to do anything and it indicates a successful mating has occurred.

To avoid unwanted pregnancies, especially in young females who are under 12-16 months old, it is important to protect your dog. Keep her at home and do not leave her unattended in your garden (determined male dogs can climb fences). Sometimes, female dogs will also make an effort to escape a garden to seek a male dog.

Most dogs cope fine with a couple of weeks without exercise, even if they are a high-energy breed. If they must be walked, it is best to road walk them on a lead to avoid male dogs. Bear in mind, a female dog will scent-mark to attract males and this could lead them back to your house.

Equal care has to be applied if you have an unneutered male dog in the same house. The dogs should be separated at all times, preferably in different rooms of the house to avoid contact. If the male is caused distress by wanting to reach your female dog while she is in season, it may be a good idea to ask a friend to look after him for a couple of weeks until she is finished.

If accidental mating occurs, there are limited options to prevent pregnancy. The most common solution is an emergency spay, which will remove any puppies that are developing and also prevent future accidents from occurring. There is also a medical treatment that will cause the dog to abort, however, it has some very unpleasant side effects for the dog and is not recommended other than in exceptional cases.

In short, it is your responsibility to ensure your dog does not become pregnant during her season and it pays to be over-cautious.

Dogs may become obsessive over their toys when experiencing a phantom pregnancy.

Dogs may become obsessive over their toys when experiencing a phantom pregnancy.

Can Dogs Have Problems After a Season?

Many dogs go through a season without an issue, but it is also not unusual for dogs to suffer phantom pregnancies after one. This is where the dog acts as if pregnant when it is not. There are varying thoughts on how common phantom pregnancies are in dogs. One suggestion is that half of all female dogs will experience a phantom pregnancy, and the longer they remain un-spayed the higher the chances of it occurring.

A dog suffering a phantom pregnancy will exhibit behavioral and physical changes. She will nest and act motherly around toys or other objects. She may make a den and become protective of it. Some dogs show aggression at this stage. Physically, she may develop swollen nipples or a swollen belly, as if she is carrying pups.

Often the phantom pregnancy will pass of its own accord within 1-4 weeks, however, once a dog has had one, it is highly likely she will have others. During the phantom pregnancy, a dog can seem distressed and unhappy, especially when puppies do not appear. This can be upsetting for both the dog and the owner. The simplest solution is to have a dog spayed after her symptoms are gone. This means she will never experience another phantom pregnancy or a season.

Myths About Seasons

There are some common misconceptions about seasons floating around the internet, here are a few you may come across and what you need to know.

Should My Dog Have a Litter of Puppies Before Being Spayed?

There is no reason for this. A dog's health is not harmed by never having puppies, while there are a number of risks involved in pregnancy, including the potential for a female dog to die. Equally, there are plenty of dogs out there and to add to the canine population is something that should only be done for very good reasons.

My Puppy Is Six months and Has Had a season. Can She Be Spayed Now?

Generally, once a dog has had a season there is no reason not to spay them, as the body should have completed maturing. However, if the dog is under a year old when they have the first season (under 2 years in large breeds), it may be advisable to wait until they are older before spaying to ensure they have finished growing. This will likely mean they will have a second season before they are spayed.

My Dog Has Stopped Bleeding; Is She Safe to Be Around Males Again?

Bleeding is only the first part of a season; when the bleeding stops is when a dog is most receptive to mating. It is important you wait at least a week after your dog stops bleeding before allowing her to mix with other dogs again.

Will My Dog's Personality Be Permanently Changed By a Season?

No. Behavioural changes are temporary and usually, dogs return to their normal selves a few weeks after a season. Spaying a dog will stop the behavioral changes associated with a season.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2021 Sophie Jackson