Shih Tzu Heat Cycle: Signs & How Many Times a Year

Shih Tzu heat cycle

Whether or not you plan to breed your Shih Tzu, it’s useful to know all the details of her heat cycle. A female Shih Tzu who has not been spayed will typically face a variety of physical and behavioral changes throughout her lifetime.

Being prepared for all of these changes during their heat cycle will make the whole journey much easier for both of you.

I am going to start off this introduction to the Shih Tzu heat cycle with some very quick pointers on how often it happens, how to tell, and how long the heat will last. I will then go into each aspect of the heat cycle in more detail.

How often do Shih Tzus go into heat?

Unless you have spayed your Shih Tzu, she will enter her first heat (also known as a season) at around six to eight months of age.

How often do Shih Tzus go into heat? After her first heat at 6 to 8 months, your Shih Tzu will then go into twice a year, typically every 6 months. Initially, her cycle may be sporadic, but after the first year or two, you should notice her reproductive cycle settling into a regular pattern.

The average Shih Tzu will go into heat once every six months. Occasionally, she might show signs of going into heat between these regular cycles, but she will typically be infertile during these additional seasons.

Shih Tzu heat how often
Your Shih Tzu will show that she is in heat with a number of telltale signs. Scroll down to see what the signs are. (Image via

Once an Shih Tzu reaches six years of age, her fertility will start to slow down. Fertility will continue to drop off until roughly ten years of age when her ability to reproduce typically ceases altogether.

That said, unless spayed, a female Shih Tzu will continue showing signs of going into heat for the rest of her life.

How do you know when your Shih Tzu is in heat?

You will know your Shih Tzu is in heat due to a range of signs including:

  • Swollen vulva.
  • Bleeding from the vulva.
  • Increased mounting behavior.
  • Licking her genital region.
  • Obvious nervous or agitated behavior.
  • Increased urination.

The Shih Tzu heat cycle length in detail

The reproductive cycle for dogs is made up of four distinct stages, each with its own physical and behavioral changes. Read about each stage below, including the Shih Tzu heat cycle length and what to expect.

1. The Proestrus stage

Typically, this is the stage that most people are referring to when they say that their Shih Tzu is in heat. On average, this initial stage of the reproductive cycle lasts nine days for most dogs, but it can last anywhere up to twenty-seven days in total.

During this stage of the reproductive cycle, estrogen levels will begin to peak in your dog, and the follicles (eggs) will start to develop. Most owners may start to notice male dogs showing an interest, although the female Shih Tzu will not reciprocate during this time.

Handy Hint: Despite what you think, spayed female dogs can still attract males for a number of reasons you might be surprised about!

If anything, she may even seem more on edge than usual. It’s not uncommon to see dogs holding their tails close to their body and becoming a little clingier with their owners during this first stage.

Physical signs include a swollen vulva and a blood-tinged discharge. Although many dogs will keep this area clean, Shih Tzus tend to have a hard time reaching this area. To avoid any messes, many owners recommend using diapers.

You may also notice your dog urinating more often during this stage.

2. The Estrus stage

This second stage can last anywhere from four to twenty-four days in total. On average, however, the Estrus stage only tends to last nine days for most dogs and marks the fertile window in a dog’s reproductive cycle.

Attention from male dogs will continue, but now the female Shih Tzu will be receptive to these advances. One of the most common ways your dog may show her availability is by “flagging”, where she lifts her tail up or to one side.

Physical changes will include an enlarged vulva and brown or clear discharge.

With the pheromones she emits during this period, the attention she receives from male dogs will be heightened.

It may also result in aggression from females, which can sometimes escalate into fights. If you have no intention of breeding your Shih Tzu during this period, it will be necessary to keep her away from other dogs as much as possible during this time.

3. The Diestrus stage

During this stage, your dog will once again lose interest in reciprocating male attention. On average, this third stage of the reproductive cycle will last two months.

Physical changes include her vulva returning to normal, and an absence of any discharge.

There are instances where she may act as though she is pregnant, even if she isn’t. If this happens, you may notice your dog exhibiting the following behaviors:

  • Restlessness
  • Lethargy
  • Reduced appetite
  • Nesting (may involve digging bedding or moving it around)
  • Nursing (may show increased attachment to a favorite toy)
  • Depression
  • Aggression

Aside from these behavioral changes, you may also notice several physical changes. Even though a loss of appetite is common during false pregnancies, the female Shih Tzu may stay at the same weight, owing to fluid retention.

Other physical changes include a swollen belly and enlarged mammary glands that may or may not lactate.

If you suspect that your Shih Tzu is pregnant, it would be best to take her to see your vet as soon as possible. Pregnancies in Shih Tzus must be carefully monitored from the onset due to the health risks involved, both for the puppies and the mother.

Handy Hint: Here are some ways you can check to see if your Shih Tzu really is pregnant or not.

4. The Anestrus stage

During the fourth and final stage of the reproductive cycle, the body will begin to prepare itself for the next season.

Typically, this final stage lasts an average of four months for most dogs, although for certain breeds it can take a lot longer. During this time, there are typically no physical symptoms or behavioral changes.

Handy Hint: There are some ways that breeders use to make their female dogs come into heat faster.

Can a spayed dog still go into heat?

Generally, no.

The process of spaying a dog means removing all the reproductive organs, including the ovaries and uterus. As this eliminates the possibility of reproducing, it also means that her heat cycle will usually stop as well.

However, if you do notice your dog showing signs of going into heat once spayed, this may be an indication of ovarian remnant syndrome.

If the surgeon misses some of the ovarian tissue during the surgery, this can result in the remaining ovarian tissue still producing estrogen. If this happens, it will continue to trigger your dog’s usual heat cycles.

It can be annoying, since this may only become obvious several months after the initial surgery. However, it is a non-threatening condition, and also relatively easy to remedy.

If you notice that your dog is showing signs of going into heat once spayed, you will need to get your dog booked in to see your vet again. Typically, ovarian remnant syndrome can be treated with a simple operation to remove any remaining ovarian tissue.

Breeding Shih Tzus

When it comes to breeding, Shih Tzus are some of the most challenging, time-consuming, and expensive dogs to breed.

Owing to the many health problems this breed faces, owners must be present through every stage of the pregnancy and delivery. Owners will also need to keep a very close eye on the litter for the initial few weeks of development to ensure that everything goes smoothly.

How to prepare for your Shih Tzu being in heat

Now you know how long and how often your Shih Tzu will be heat, it’s time to get prepared. By doing so, you can guard against your girl getting pregnant unexpectedly, leaving messy blood spots on the floor, and even possible changes to behavior including aggression.

Here’s how you get prepared using some inspiration I found on

1. Track her heat cycles

On the day your Shih Tzu starts her heat cycle, place a note on your calendar. I’d use your phone’s calendar as you can record day 1, and then put a reminder in that it could come again in 6 months’ time.

Set the reminder up a week before the 6-month point, as that gives you time to prepare again.

2. Buy dog diapers

A dog in heat will leave blood spots and mess on her bedding and the floor. You can mitigate this by using specialist dog diapers.

If you don’t want to spend this money you can use human baby diapers but will need to cut a hole out of the back of them for the tail to come through.

3. Think about security

Some dogs will try to escape during their heat cycle and can show aggression. If this sounds like your Shih Tzu, think about keeping her secured using door gates, or just being more vigilant than usual – perhaps an off-leash walk isn’t a good idea during this period!


My wife and I recently looked after a female Shih Tzu who came over to play with our Frenchie, Claude. The female hasn’t been spayed yet, so it wouldn’t surprise me if she started to show signs of going into her first ever heat cycle very soon – she’s 7 months old.

When that happens, our friend will need to be prepared, as the Shih Tzu heat cycle can be quite a shock if you’ve never owned a female dog before.

I’ve told them to be prepared for some changes to her personality!

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There’s a wealth of information on the DoggySaurus website about Shih Tzu ownership:

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Marc Aaron

I write about the things we've learned about owning dogs, the adventures we have, and any advice and tips we've picked up along the way.

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