Everything you wanted to know about the female season

Posted Sunday, 20 January 2019

How to avoid unwanted pregnancy

Many clients have asked me about seasons (also known as heat) cycles so they can make sure their female (also known as “bitch” ) does not accidentally become pregnant, so I thought a short article would be helpful.

When do female dogs come into season?

This can vary by individual and breed. Typically, a female will come into season at around 6 months old, but it can occur from 4 months up until more than two years. Some breeds, such as the whippet, tend to come in to season around 13 months. It’s a good idea to ask your breeder what age the mother dog first came into season as this can be a useful guide as to when to expect your female to come into season. If you are aiming to breed (and don’t enter into this lightly, it’s an enormous responsibility as well as expensive if you do it properly), it’s very important NOT to let a female mate for the first two seasons due to lower egg quality and also because you will not know her temperament and her joints will not be developed enough for carrying a litter. A female will usually come into season twice a year, but once a year for giant breeds.

How long does a season (heat) last?

Typically, between 2-4 weeks, this is why we ask you to give your female dog four full weeks before coming back to training classes if she comes into season during one of our training courses. By the way, because a season is impossible to accurately predict, we will offset your missed sessions against the next course, so you will not be out of pocket.

When should I avoid letting my in-season female meet intact (uncastrated) male dogs to avoid a pregnancy?

To answer this I will need to explain a little about the dog's reproductive cycle.

Proestrus stage:

The proestrus stage is the first stage of a heat cycle and it lasts approximately 9-10 days, during this time she will normally be bleeding. Sometimes you don’t see the blood if your female is very good at keeping herself clean. But you would notice her cleaning herself more. She will also very likely urinate more as she is marketing her fertility state to other males in the vicinity. You will also notice that her vulva (female genitals) will swell up significantly and will protrude outwards. Mostly, (but not always) the female will not be interested in mating a male at this time, even if he is interested in her. After about 9-10 days, the bleeding will become more watery, or stop. It is at this time your female will, most likely, be at her most fertile. This proestrus stage can last as long as 20 days in some dogs. So the end of bleeding can be a more useful indicator of peak fertility.

Estrus stage (FERTILE STAGE):

The estrus stage occurs after the proestrus stage, approximately from 9-10 days to 15-19 days. During this stage, your female will most likely be very receptive to being mated by any male and will even hunt them down and offer herself (fluzy!). Every male in the district will be tracking her by scent. There will be nothing you can do to stop her being mated if you take out your female, and you will likely end up with an unwanted litter. Many people think that once the bleeding stops, the season is over, when in fact, usually, when the bleeding stops and becomes more watery, she is at her most fertile and most likely to get pregnant. However, it is important to note that it can be possible for your female to become pregnant right up until the end of her season, up to four weeks. After estrus stage, the vulva should return to normal, at this stage, she is no longer fertile and she is safe to mix with intact male dogs.

Diestrus stage:

This is the stage that follows oestrus. The female will no longer be receptive to being mated. This stage lasts for about two months. Progestrone levels will peak three - four weeks after the start of diestrus and then revert to normal levels by the end of this stage. These hormone levels change regardless of whether or not the female is pregnant. As these hormone changes are occurring, it is important not to spay a female until after this stage. It is the ovaries that regulate the hormones, once removed, they will not be able to regulate hormone levels. This can leave your female in a state of unbalanced hormones, which can lead to ongoing behaviour problems if hormonally mediated behaviour problems occurred during the season. 

Phantom Pregnancy

Some females will develop what is known as a "phantom pregnancy" during the diestrus stage. She will produce milk and you may see behaviour changes such as protection of resources and nesting. Some females manage this stage with no problems, but sometimes behaviour problems can occur. Also, it has been suggested that phantom pregnancy could pre-dispose the female to developing pyometra, a potentially fatal infection of the uterus. If your female's behaviour changes during this stage, it is worth speaking to your vet. Monitor for elevated temperature (making sure that you use an ear thermometer, or lubricate the thermometer if inserting this anally to avoid inflicting pain and discomfort on her). The first signs of pyometra can often be changes in behaviour such as going off food, becoming lethargic. There will usually be a smelly discharge from the vulva. At this stage an emergency vet visit is necessary. Pyometra can kill very quickly.  

Etiquettes for walking an in-season female.

Please don’t walk your in-season female dog in public. Her scent will attract every intact male in your neighbourhood. Even castrated dogs will hunt down the scent of an in-season female and even a castrated male dog can “mate” with her. The mating (tying) process can take many minutes (typically half an hour) during which time, your female and the male will be locked together.  Better to avoid this embarrassment. You will not want just ANY dog to mate your bitch. Dogs can carry sexually transmitted diseases just as humans can, one of which is a sexually transmitted form of cancer! Also, you should be carefully choosing a mate based on being free from genetic disorders and having an exemplary (perfect) temperament.

Please be responsible. there are so very many dogs in rescue centres, the last thing anyone needs is more unplanned litters. Only breed from your dog if you are prepared to breed from dogs that have no behaviour problems (especially aggression), undertake DNA testing and are knowledgeable about how to choose the right sire for your female. Breeding a litter is not an easy thing that you must leave to the mother dog. You will need to be at home with her for several months to supervise and provide appropriate support. Preparing to breed an ideal litter will cost you in excess of £1,000.00 before you even have the litter. C-Section is common and can cost several thousands of pounds. Having a properly planned litter is not a profitable activity.



How do I know if a male dog is castrated?

If you look at the male dog from behind, if a dog is not castrated, you will be able to see his testicles. If there are no testicles, perhaps just a flap of skin hanging down, the dog has been castrated, or chemically castrated.

Can my uncastrated dog still mate with an in - season female?

Your dog can still tie. This means he will penetrate the female but, if he has been castrated, he will not be able to impregnate her. However, the tie can last for many minutes (typically around half an hour), during which time you will not be able to separate them. You should never try to separate them when tied as you could cause injury. 

How do I prevent my intact male dog from mating my in-season bitch when they live together?

Please do not keep them together during this time. The male will likely become very frustrated at not being able to reach his fertile friend, and this can - and does - lead to aggressive outbursts. Male dogs can be very creative at finding ways to get to an in-season female, it would be almost impossible to prevent them from mating.  Be fair on him and board him with a friend or family member until her season is finished.

Can my female dog get pregnant from more than one male dog?

Yes, you can have puppies from different fathers if your dog has mated more than once. This is called “mixed paternity litter”.


Denise Nuttall B.Sc (Hons), M.Res

Full Member APBC (Association of Pet Behaviour Counsellors), Full Member TCBTS (The Canine Training & Behaviour Society)

Animal Behaviour & Training Council (ABTC) Registered Animal Training Instructor 
Animal Behaviour & Training Council (ABTC) Registered Clinical Animal Behaviourist