Last Updated on June 8, 2023 by Becky Roberts
When your puppy girl reaches the age of 6 months or more, you’ll see her menstruate for the first time. That means she’s reached sexual maturity and can (technically) start having puppies. Assuming you will allow her to reproduce (and have no immediate plans on spaying her), you might think it’s still too soon for her to start having babies.
And you’d be right. At less than a year, she might not be big and strong enough to birth and nurse a litter of pups. Keeping her not pregnant until then would be important.
So if you’re a first-time parent, inevitably you ask the question, “Can a dog get pregnant when not in heat?” (Some people insist this can happen.)
Well, no. And here’s why.
Clarifying the term “in heat”
When people say a dog is “in heat,” they simply mean she’s displaying the following symptoms: a swollen vulva, bloody vaginal discharge, and a scent that draws males in like a magnet.
But these three symptoms are present during the proestrus, estrus, and diestrus stages of a dog’s reproductive cycle — and she can get pregnant only during estrus.
A dog’s reproductive cycle
Female dogs have 4 stages in their reproductive cycle or “heat cycle.” They get pregnant only if they succeed in mating during the second stage.
Stage 1: Proestrus
Typical length: 9 days
The first stage is when estrogen levels in a dog’s body begin to peak and the eggs in her ovaries begin to mature. This is accompanied by the swelling of her vulva and bloody vaginal discharge. (This is the canine version of menstruation.) Your dog will be more restless and urinate more often.
During proestrus, her scent and appearance will also attract the attention of male dogs. But she won’t be mentally receptive to their advances. (She may get frightened or angry by their presence.)
And even if a male dog somehow managed to force his way on her, she won’t ever get pregnant at this stage. The ova (eggs) simply aren’t out and ready for fertilization yet. Any male dog’s sperm that might find its way in will not survive long enough to see them released.
Stage 2: Estrus
Typical length: (varies greatly) 4 to 24 days
Estrus is when your dog’s estrogen begins tapering off, and progesterone level starts to increase. The ovaries finally release the mature eggs. Her vulva remains visibly swollen and soft, and there’s still some blood-tinged vaginal discharge.
More importantly, it’s when the ovaries finally release the mature eggs. It’s the window of opportunity for your dog to get pregnant. Your dog is still attracting male dogs at this point. But this time, she’s mentally and physically receptive to mating with them. If she copulates with a dog during this stage, she will definitely get pregnant.
Stage 3: Diestrus
Typical length: 60 to 100 days (normal) or 56 to 58 days (if pregnant)
In diestrus, your dog’s estrogen levels finally reach a low point, while progesterone peaks. There will still be some bloody vaginal discharge. But the swelling of her vulva will begin to go down and your dog will no longer accept “courting” male dogs.
Note: in terms of hormone levels, diestrus and actual canine pregnancy are similar. So whether your dog has gotten pregnant or not, you’re going to see her tits swell a bit and express a bit of milk. (She may even put on some weight and instinctively look for “nesting” places to sleep in.)
Stage 4: Anestrus
Typical length: 4 to 5 months
Essentially, this is your dog’s reproductive “quiet time.” The vulva is back to its normal size and there is no more vaginal bleeding. Your dog no longer attracts males with her scent.
Related: How Long Do Dog Periods Last?
Points of Confusion
So why do some people think a dog can get pregnant anytime? It’s probably because of the following:
Variations in frequency
On average, dogs experience two reproductive cycles in a year (i.e., every six months). But this can vary greatly between individual dogs. Sometimes it’s due to a dog’s breed; sometimes it’s due to age.
In smaller breeds (e.g., Chihuahuas), it’s not unusual for adult female dogs to go through as many as 3 or 4 “heat cycles” a year. Meanwhile, larger dogs (e.g., St. Bernards, Irish Wolfhounds, and Great Danes) tend to have only one reproductive cycle per 12 to 18 months. A few notable exceptions are medium-sized hunting or working dogs like the Basenji and the Alaskan Husky.
Also, younger dogs start with irregular frequencies. It takes them a year or two to develop a more regular cycle.
This wide range of variation can confuse new pet parents and make it difficult for them to know exactly when their baby is fertile.
Phantom pregnancy
As earlier mentioned, your dog’s body symptoms and behavior during the diestrus stage can look pretty much like early pregnancy.
And there’s also pyometra, a life-threatening uterine infection that female dogs can develop at any age (though it’s more common in older dogs.)
Pyometra can develop when the uterus gets contaminated with bacteria. While bacterial growth is encouraged the most during the great hormonal changes in estrus, the disease can show up anywhere from 2 to 8 weeks after estrus. Pyometra’s early physical signs can look similar to those of early pregnancy — a faint bloody discharge from the vagina, increased body temperature, and a gradually swelling abdomen. (Only a blood test can check for an elevated white blood cell count and help diagnose uterine infection in its early stages.)
All these false pregnancies may confuse inexperienced dog owners into thinking their dog might have been fertile even when not “in heat.”
Being sure
So how would you know precisely when your dog is fertile?
If you’re willing to spend some extra bucks, you can get your vet to perform a series of tests. Those will include a physical exam, a vaginal smear test, or a progesterone test. These can provide conclusive proof of when your dog can get pregnant.
What to do while she’s in estrus
OK, now that you know all of this… is there something you should be doing for your dog while she’s in heat? Here are a few tips.
Tip 1. Be patient and adapt to your dog’s mood.
During the hormonal and physical changes that occur in the first three stages of her reproductive cycle, your dog may have these “mood changes” or behavioral changes. She can get “clingy,” pining for more cajoling or affection from you. Or she may become grumpy and want to relax alone in the quieter corners of your home.
Be patient with your dog. Beyond making sure she sticks to her usual routine (eating, sleeping, bathroom breaks, exercise), just let her be or give her the love and attention she craves. A dog in heat can easily get upset. If you ignore her or snap at her in anger, she can be moody enough to hold a temporary grudge against you (e.g., sulk in a corner or ignore you in turn) or throw a “tantrum” (e.g., chew up a few magazines or pillows in the living room).
Tip 2. Let her lick herself.
A dog in heat will also have the urge to “bathe” or routinely bite-scratch and lick at her vulva and the adjacent areas. Don’t dissuade her from doing this. It’s only natural and it won’t harm her, as long as she’s regularly drinking clean water and you keep her clean.
Tip 3. Be gentle with grooming and bathing.
Speaking of keeping your dog clean: be careful and extra gentle when you bathe her during this time. Her vulva and nipples will be swollen and extra-sensitive to the touch. If you handle her roughly around her mammary glands or the lower half of her body, it’ll be painful for her.
Tip 4. Keep your home and garden secure.
When we say “secure,” we mean keeping the front yard and back portions of your property fenced or secure.
Because the scent of your dog in heat will last several days, it will be enough to draw in all the male dogs in the neighborhood. You’re going to have to keep your dog fenced in from them, or you’ll never get to manage your dog’s pregnancy.
Moreover, these wandering male dogs will try to mark your property (and by extension, your dog!) as their “territory.” They’re likely to pee a lot or even poo around your home.
In conclusion
So remember: dogs can only get pregnant when they’re “in heat” or estrus.
And if it’s too much of a bother for you to worry about your dog becoming pregnant, you can have her safely spayed.
Also Read: Can Dogs Get Abortions?
