How Long are Female Dogs in Heat?

How long are female dogs in heat? Generally speaking, a female dog will be in heat for around 2-4 weeks, but this will vary and has different stages.

Female dogs will reach sexual maturity (puberty) at around the age of 6 months, but this can take longer for larger breeds.

Once they reach this stage, you will likely notice some bleeding and behavioural changes in your dog, as her body prepares for a potential pregnancy.

Once a female dog starts this cycle, she will continue for the rest of her adult life.

Being in heat is also known as being in season.

What are the symptoms of a dog in heat?

You will get to know when your dog is in heat by the telltale signs.

These are:

  • licking her back end more often
  • a swollen vulva
  • bleeding/discharge from the vulva. This is usually coloured red, but can also be a yellowy-brown colour. Your dog may keep herself clean, but you may notice drops of this on the floor, depending on how heavy the flow is
  • urinating more frequently
  • other dogs sniffing her rear (usually male)
  • moving her tail to one side when being stroked
  • mounting other dogs (yes, girls do this too)
  • anxious behaviour
  • nesting
  • an increased interest in other dogs, especially males

How often are dogs in heat?

The average frequency is around every 6 months but can be more frequent for smaller dogs and less frequent for larger breeds.

For example, a Great Dane will go into heat around every 12-18 months or so, whereas smaller breeds can cycle every 4 months, going into season up to 3 times a year.

Is my dog in pain when in heat?

It’s unlikely that your dog is in pain when in heat. She could be feeling a bit uncomfortable though.

If she is howling and making yelping noises, it’s probably due to frustration – as she wants to find a mate.

This will usually pass when she moves on to the next cycle.

If you do have any concerns though, speak to your vet.

What are the stages of a dog in heat?

There are 4 phases to your dog’s heat cycle. Once your dog has reached puberty, she will always be in one of these stages.

Phase 1 – Proestrus

During this phase, your dog’s estrogen and progesterone levels start to rise in preparation for pregnancy.

Her vulva will usually swell and some bleeding will start from her vaginal area. Due to this, she will likely be licking herself more often.

Phase 2 – Estrus

The next stage sees the bleeding slow and changes from a red colour to a pinker shade, eventually stopping completely.

This stage is when your dog is at her most fertile, so you need to be extra careful if you do not want her to mate.

The estrus stage is what many people refer to as being ‘in heat’, as your dog will be looking to find a partner.

Phase 3 – Diestrus

Female dogs experience this stage whether they are pregnant or not. Her nipples and mammary glands will become swollen in preparation for milk production.

Some dogs will actually produce milk, even though they are not pregnant.

This (along with other signs) is known as a false pregnancy and is thought to happen in certain dogs due to the fact that they are pack animals.

It was often beneficial to have other females producing milk for the pack’s puppies, even though they weren’t actually pregnant themselves.

More on this here.

Phase 4 – Anestrus

This phase is what your dog is in most of the time. So their ‘normal’ phase so to speak.

Your dog’s hormones will decrease back to normal levels and stay that way until her heat cycle starts again in a few months time, which will begin with phase 1 – estrus.


Once your dog starts her heat cycle, she will continue to be in one of the 4 stages for the rest of her adult life.

She will be in the heat for around 2-4 weeks.

It’s a good idea to make a note in your calendar of when she is in heat so that you predict when her next season will be and help you plan.

Unless you want her to get pregnant, keep a very watchful eye on her when she is in heat, especially in stage 2, as she likely will be actively seeking a mate.

Why not save How Long are Female Dogs in Heat? to Pinterest for future reference.

Dog diapers

Did you know you can get dog diapers (nappies) for when your dog is in heat and bleeding?

This helps keep your dog and home a lot cleaner.

Have a look at the ones in the links below if you are interested.

Links: USA | UK