Dogs In Heat: Timeline, Duration, and Symptoms
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When a female dog is in heat (known as estrus), it’s normal part of their regular cycle of fertility when they are not spayed.
As a pet parent you may be wondering, “What is heat in dogs” or “How long are dogs in heat?”
There are many behavioral and physical changes you will recognize and it’s important to know how it will affect your dog.
Knowing things like how often a dog comes into heat and how long it lasts will help you be prepared.
Key Takeaways
- A female dog’s reproductive cycle is called an estrous cycle and has three phases.
- Dogs can have their first heat when they’re as young as 6 months old or as old as 24 months of age.
- Having dogs spayed is the most common, safe, and effective method for preventing unwanted dog pregnancies and reducing pet overpopulation.
How Often Do Dogs Go Into Heat?
Female dogs usually go into heat twice a year, about every six months.
However, depending on your dog’s breed, age, and breeding status, the length of time between estrus can be as much as 11 months—meaning some dog breeds are only in heat about once a year.
How Long Are Dogs In Heat?
Dogs can be in heat up on average for 14–21 days.
This is the period in which a dog is fertile and able to get pregnant. Just like how often they come into heat, the length of a dog’s heat cycle can vary as well, depending on the same factors.
Phases of a Dog’s Heat Cycle
A female dog’s reproductive cycle is called an estrous cycle and has three phases:
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Proestrus is the beginning of the heat cycle. It’s characterized by swelling of the vulva and a blood-tinged vaginal discharge. Female dogs will not allow mating to occur in this phase. This phase can last anywhere from a few days to four weeks. On average, it lasts seven to 10 days.
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Estrus is also known as “heat.” This is the time when the female dog will allow mating to occur. This phase of the cycle lasts anywhere from three to 21 days, with an average length of nine days.
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Anestrus is defined as the timeframe when cycling ceases. This phase usually lasts about four to five months.
When Do Dogs Go Into Heat?
Dogs can have their first heat when they’re as young as 6 months old or as old as 24 months of age. Even though dogs can become pregnant during this timeframe, it’s generally not advisable, as they are still not fully mature.
The timing of a dog’s first heat varies, with size being a major factor.
Small-dog breeds tend to have their estrus cycle at an earlier age (around 6 months old), while large- or giant-breed dogs may not come into heat until later (18–24 months).
Symptoms of a Dog In Heat
Symptoms of a dog in heat include:
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Swollen nipples
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Swollen vulva
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Bloody or pink vaginal discharge
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Restlessness
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Licking vulva excessively
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Change in behavior (sometimes more affectionate or aggressive)
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Increased attention from male dogs
Do Dogs Go Through Menopause?
Dogs do not go through menopause.
Because their reproductive cycles are different than that of humans, dogs can continue to go into heat and subsequently become pregnant throughout their lives, even into their senior years.
You may notice, however, that your dog’s cycle may occur less often, or the duration seems longer from one heat to the next. That’s normal in dogs as they age.
However, dogs that have stopped having cycles altogether should be examined by a veterinarian, as this can signal an underlying health condition or metabolic disease process.
But just because dogs can get pregnant as seniors doesn’t mean they should.
Litters from senior mamas tend to be smaller, there may be more puppy deaths, and labor may be more difficult if carried to term.
Females dogs over 8 years of age are also more at risk of developing pyometra, a life-threatening uterine infection.
What To Do When Your Dog Is In Heat
From dog diapers to body wraps, there are multiple at-home, nonpermanent ways to prevent pregnancy and to keep your home clean during your dog's heat cycle.
If you choose to use a dog diaper, keep in mind it should be leakproof, absorbent, comfortable, and most importantly, secure. It should also be changed frequently (every three to four hours).
If you have male and female dogs in your house, use dog crates, dog gates, and closed doors to ensure they are kept separated when your female dog is in heat.
Do not frequent dog parks or other dog-populated areas while your dog is in heat.
Unfortunately, preventing your dog from getting pregnant is not as easy as it sounds.
Don’t underestimate the determination of your dog—or someone else’s—to reproduce. Extra vigilance is needed, and having a fenced-in yard is not enough.
Having dogs spayed—which involves removing the ovaries and/or uterus—is the most common, safe, and effective method for preventing unwanted dog pregnancies and reducing pet overpopulation.
A dog spay procedure is permanent and can’t be reversed.
Dogs In Heat FAQs
Do dogs get periods?
A heat cycle can be compared to humans when they get their period. A female dog goes into heat approximately twice a year. This process is part of their fertility cycle.
What are common behaviors of a female dog in heat?
Common behaviors for dogs in heat are restlessness, increased aggression or becoming more affectionate, increased urination, and licking their vulva.
Physical changes can also include a swollen vulva, swollen nipples, and bloody vaginal discharge.
Do male dogs go into heat?
Male dogs do not go into heat because they do not have a uterus.
How do male dogs know a female dog is in heat?
Male dogs know that female dogs are in heat because the females emit pheromones. Pheromones are found in a female dog’s urine and vaginal discharge.
