What to expect when your female dog is in season

Generally, we recommend speying (also known as sterilisation or desexing) female dogs at around 6 months of age at Your Pet’s Vet. This surgical procedure involves complete removal of the uterus and ovaries, and the female dog will not come into season in future.

Some owners prefer to allow their dogs to have a season, or plan to breed in the future and in these cases, the female dog will have oestrus cycles, generally twice a year ongoing.

Please note that an emergency caesarian can cost between $3,000 to $5,000 so please ensure you are financially prepared for this possibility.

If you do not want an accidental mating, it is important to know what happens in a normal cycle. There are 5 stages of the reproductive cycle and these are known as pro-oestrus, oestrus, metoestrus, dioestrus and anoestrus.

The “season” (window of fertility) is from the start of pro-oestrus to the start of dioestrus and generally this lasts around three weeks.

Stage 1 - Pro-oestrus

At the start of pro-oestrus, the levels of oestrogen will rise in anticipation of the release of the eggs and the uterus will start to swell. During this time there will be physical and behavioural changes in your female dog that can include:

She will likely urinate more, and this is a way for her to leave a message for male dogs to let them know she is in season.
She may become more outgoing and flirtatious as she attempts to attract suitors. Although, at this stage, she will not let them mount her. She may stand with her hind quarters towards the dog and move her tail to one side to allow the dog to better see and smell that she is nearing her most fertile time.
Physically, her vulva will swell and become a more red/pink colour.
She will start to bleed or spot and this is more noticeable in some female dogs than others. Some are so good at keeping themselves clean, so it is barely noticeable.
She may become less obedient and try to escape (boy chasing!).

This stage of the cycle will last an average of 9-10 days but this varies individually and across breeds.

Stage 2 - Oestrus

The next stage of the cycle, oestrus, coincides with ovulation and the release of the eggs. Over the next 5 or so days she will allow herself to be mounted. Physically her vulva will become even more swollen, and a straw coloured/ clear discharge will often be seen.

Many owners think the fertile period is when the discharge is bloody/pink, but it is actually AFTER this that she is most likely to become pregnant.

Stage 3 - Metoestrus

During this phase things start to return to normal. She will be less excitable; her vulva will return to its usual size and colouring, and discharges will stop. She will not allow mating and her body starts to produce progesterone that will line her uterus in readiness for pregnancy.

Stage 4 - Dioestrus

At the Dioestrus stage, progesterone is still being produced. In nonpregnant female dogs the high levels of this hormone can lead to phantom pregnancies – this is when the female dog can appear pregnant (swelling, milk production and nesting behaviour despite not being pregnant).

Stage 5 - Anoestrus

Anoestus is the much longer period between the seasons until oestrus starts again.

Any female can be at risk of Pyometron; an infection in the uterus. Signs of this include increased thirst, vomiting, lethargy, sometimes with a vaginal discharge. Pyometron is often found in the weeks after a season. Pyometron is life threatening and you need to see a vet if you notice these symptoms in an unneutered female dog.