How long is a dog in heat and other pertinent questions pet owners have

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Heat cycles in dogs are a natural occurrence, and many pet owners wonder about the heat cycles in their dogs and how it affects their bodies and ability to have pups. If you are adopting or purchasing an unspayed female dog or puppy you should know about their heat cycles. The primary question of many owners is, “how long is a dog in heat”?

On average, a dog’s heat cycle can last anywhere from 3-4 weeks and since each dog is different there are several factors that dictate how long your dog’s heat cycle will last including age, breed, size, and weight. Let’s discuss some reasons for the differences.

One common question asked is if dogs get a period? As a whole, if your dog is unspayed they will have a ‘period’ or an estrus cycle. A dog’s estrus cycle is also termed being “in heat” or “in season”. During a dog’s heat cycle or estrus cycle, there is a period where you may notice blood or discharge and many owners wonder how long this will last and the best ways to keep their homes clean, we will discuss that below.

If you are adopting a young unspayed female dog or getting a female puppy you may be wondering when their first heat cycle will start and how long does the cycle last.

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At what age will my dog have her first heat?

On average, most dogs will go into heat or start their first estrus cycle when they reach puberty around six months of age. However, even though the average time period for dogs to reach puberty and start a heat cycle is six months this number can vary depending on breed. Smaller breeds of dogs tend to mature earlier than larger breeds and may have their first heat a lot earlier. For example, a Yorkshire Terrier may go into heat at 5 months and a Great Dane may start her estrus cycle at 1.5 years of age.

Common signs that your dog is in heat

Common signs of a heat cycle in dogs include

  • You may notice some redness and swelling around your dog’s vulva before and during estrus
  • During your dog’s heat cycle you may notice some bleeding from your dog’s vulva
  • You may notice some blood-tinged discharge from your dog’s vulva
  • Your dog may be slightly more agitated, irritable, and even aggressive around her heat cycle

How long does the heat cycle in dogs last?

On average, the entire heat cycle lasts in dogs around 3-4 weeks but can vary widely depending on the breed of dog. There are four stages to your dog’s heat cycle, proestrus, estrus, diestrus, and anestrus which make up the three to four-week period.


Proestrus is the first phase of a dog’s heat cycle and lasts an average of 8 days, however, it can be as short last 2 days or as long as three weeks.

During proestrus, the female dog becomes attractive to male dogs but she does not allow him to mount her.

You may notice swelling of the vulva, some discharge which is usually blood-tinged and an increase in temperature may occur


The second phase of a dog’s heat cycle’ is estrus, this is the period where the female dog allows males to mate with her. During estrus, your dog may show signs of wanting to be mated by lowering her head to the floor while her rear and vulva are up for the male to see or holding her tail to one side.

The estrus phase of a do’s heat cycle is the only time she can get pregnant. The estrus phase in dogs lasts about 7-9 days, although it varies depending on the dog.

During the estrus cycle, you may notice bleeding during the first half of the cycle as dogs tend to bleed for only 7 -10 days. Some dogs may bleed a lot while you may not notice much blood on others. The vulva becomes soft and wrinkly as the dog nears the end of estrus per the Merck Veterinary Manual.


The third phase of a dog’s heat cycle is diestrus. During the diestrus phase, the female dog may seem to be extremely aggressive towards any male that attempts to mate with her as she is no longer receptive to mating. Diestrus lasts for an average of 100 days and can be anywhere from 10-140 days.


The fourth phase is anestrus which is the inactive period of the cycle and usually lasts between 1-6 months.

Why do dogs urinate more during their heat cycle?

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Female dogs urinate more during heat to attract their mate, researchers believed that urine is a source of sex pheromones to attract males.

Oftentimes, before a male mates with a female, he may sniff and lick her vulva which sometimes has a small amount of urine. Some researchers believe that the compounds in a female’s urine help the male decide if they will mate with her.

In some cases, your dog may urinate more when on their heat cycle, and they may have a urinary tract infection, especially if she wears diapers and they aren’t cleaned regularly.

How to calculate your dog’s heat cycle?

Take note of your dog’s first day of heat and count the next 10-14 days which may complete the cycle. Keep track of your dog’s next cycle so you can determine how often she comes into heat. This will be about six months after this heat.

How to keep your house clean with a dog in heat?

Understandably, most owners don’t want to separate their pups or place them in a crate while in heat so here are some things you can do to keep your home blood free

Hydrogen Peroxide

When hydrogen peroxide encounters the enzyme catalase it causes an oxidizing reaction. Apply a small amount of hydrogen peroxide to the stain and let it sit for at least five minutes. Blot it with a towel or paper towel and rub gently with a damp cloth until gone. If you can wash the item with cold water to rinse out any residual hydrogen peroxide.


Putting your dog in diapers is a great option to keep your home clean and blood-free when you have a dog in heat. Make sure you change the diaper often and wash them if they are disposable to prevent urinary tract infections and possible rashes from occurring.

Use puppy pads

Use puppy pads or old towels to line your dog’s bed to keep it free of blood

Invest in washable beds. Usually, no matter how careful you are about keeping your dog’s area clean you will most likely notice blood in some areas. It is best to invest in washable bedding for this reason.

Don’t allow your pet on the furniture

Many pet owners don’t allow their dogs on the furniture during this time or they will cover the common areas like the couch.

Use pet wipes

Invest in wipes to clean your pet regularly

Give a bath

If needed give your dog a bath, although you don’t want to bathe her too often as this may dry out her skin

How do I know my dog’s heat cycle is over

You will know that your dog’s heat cycle is most likely over when her vulva returns to its normal size and you don’t notice any more discharge or blood

you’ll know the cycle is over when all her vulva returns to its normal size and there’s no more bleeding or discharge.

Can I stop my dog’s heat cycle?

The only way to prevent estrous and stop the bleeding is by spaying your dog. While short-term suppression of estrus can be achieved by medication most owners will spay their dog if they don’t plan on breeding their dog.