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How Long Is a Shih Tzu in Heat? Everything You Need to Know

Jessica Kim

By Jessica Kim

Cute Shih Tzu the dog looks at the owner with sleepiness.

Shih Tzus are a popular toy breed known for their affectionate personalities and strong loyalties. Their wonderful personalities and small size make them sought after by many dog lovers.

Breeding Shih Tzus isn’t particularly challenging, and many experienced breeders are able to produce healthy litters with few complications. Female Shih Tzus typically have two heat cycles in a year, and they last between 2 to 4 weeks each. Being familiar with a Shih Tzu’s heat cycle can increase the chances of successful breeding and help Shih Tzus give birth to healthy puppies.

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Shih Tzu Heat Cycle

Female Shih Tzus usually reach sexual maturity when they’re between 7 to 10 months old. Keep in mind that this is an estimate, and individual Shih Tzus can become sexually mature earlier or later than this age range.

It’s possible for Shih Tzus to start their first heat cycle when they’re 6 to 15 months old. Shih Tzus that haven’t been spayed and haven’t had their first heat cycle by 15 months old should be seen by a veterinarian to ensure their growth and development is on a healthy track.

There are four stages that a Shih Tzu goes through in one heat cycle. The proestrus and estrus stages signal preparations for mating, while the diestrus and anestrus stages signify that a Shih Tzu isn’t ready to mate.

Proestrus Stage

This stage usually lasts between 7 to 10 days. During this time, a Shih Tzu will produce pheromones that attract other dogs. However, she won’t be interested in mating and may show aggression toward other dogs.

Shih Tzus in the proestrus stage will have a swollen vulva that may also be redder than normal. They may also lick the genital area more frequently, and there’s usually bloody discharge. The first day of bloody discharge indicates the first day of a new heat cycle, so it’s best to mark this day on a calendar to help keep track of the entire cycle.

Estrus Stage

This stage is what most people refer to when they say that a dog is “in heat.” It lasts between 5 to 14 days and is the fertile period when a Shih Tzu is able to become pregnant. You will continue to see discharge from the vulva, but the color will be lighter throughout the entirety of this stage.

Diestrus Stage

The diestrus stage will last between 60 to 90 days after the last day of the estrus stage. Shih Tzus that were successfully bred during the estrus stage will enter pregnancy during this period. Unpregnant Shih Tzus will continue to express darker discharge and attract unwanted mates.

Anestrus Stage

The anestrus stage is the period between the end of the diestrus stage and the beginning of a new heat cycle. Shih Tzus will not be fertile during this stage, and their behavior will revert back to normal. The length of this stage lasts between 60 to 90 days.

Shih Tzu Showing Teeth
Image Credit: Marissa B., Shutterstock

Signs That a Shih Tzu Is in Heat

One of the best ways to track a Shih Tzu’s heat cycle is to use a calendar and mark out the start of the proestrus stage. You can also look for a few signs that may indicate that a Shih Tzu is in heat and ready to mate.

During the estrus stage, the Shih Tzu’s vulva will still be enlarged. The discharge will be a lighter color. Shih Tzus will also be more willing to mate and won’t show strong signs of aggression towards males. They may want to go outside more often and will wag their tails as a sign of their readiness to mate.

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A Shih Tzu’s full heat cycle can last between 2 to 4 weeks. The time she’s in heat will be during the estrus stage, which can last between 7 to 10 days. While Shih Tzus will start to display certain signs and behaviors to indicate they’re in heat, you can track heat cycles more accurately by using a calendar, marking down the days, and taking note of any accompanying symptoms.

Featured Image Credit: Phonpipat Jampatip, Shutterstock

Jessica Kim

Authored by

Jessica is a freelance writer who spends most of her day researching and writing while her fluffy Cavapoo, Nora, naps beside her. She loves and appreciates pets and animals because there’s so much to learn from them, and they do so much for people. As a dog mom, she understands the special connection that pet parents have with their pets. So, she loves sharing helpful information that people can use to better understand...Read more

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