Dog’s Nipples Become Swollen in Heat – What Does It Mean?

When your dog is in heat, her body experiences various hormonal changes. This situation may make you wonder, “Does a dog’s nipples get bigger when in heat?”

When your dog is in heat, her nipples may become swollen. This symptom doesn’t always accompany the heat cycle, but it is common. There are a few explanations as to why. Swollen nipples disappear around the conclusion of the cycle.

Pet owners may be unaware of all that accompanies a dog entering her season. In this article, we’ll explain what’s happening to her body and what to expect. Keep reading to learn more!

Why Do a Dog’s Nipples Become Swollen When She’s in Heat?

When the heat cycle occurs, you may not notice that your dog’s nipples are bigger, as the onset of the process doesn’t trigger an increase in size. However, when the cycle is nearly complete, you might see that the mammary glands and the nipples are swollen because of the peak progesterone levels.

As a pet owner, don’t be alarmed if you see the nipples become larger; it’s the body’s natural response. Your dog could also seem more frustrated and on edge when she’s in the season. It might cause her to excessively lick the nipples and vulva, making them even more sensitive and swollen from constant manipulation.

What Does It Mean When Your Dog Is in Heat?

When your female dog enters her “season,” also known as being in “heat,” she’s in the fertile stage of the reproductive cycle.

During the heat or estrus phase, her estrogen levels will first increase, then drastically decrease, and her ovaries will release mature eggs.

While many pups happen to be close to six months when they experience their first heat, it can range from four to two years. This age discrepancy may be related to size, as smaller dogs may start younger than average and larger breeds later.

How Often Does a Dog Go Into Heat?

Although there is a range for how often the heat cycle occurs, dogs usually go into heat every six months. In the beginning, however, this number may not be so consistent, so it’s something to keep an eye on. Your dog might require between 18-24 months before its cycle becomes regular.

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Small breeds usually go into heat more often, even three to four times per year. Large to extra large breeds such as St. Bernards and the Great Dane may only be in heat once a year.

When your dog finally goes into heat, expect it to last around 21 days, but it can also be anywhere from 14-28 days. This occurrence lasts a lifetime, but they’ll be further apart as your dog ages.

Over time, owners become familiar with the signs that it’s starting and how they can take care of their dog as it’s happening.

How Long Will It Take for a Dog’s Nipples to Return To Normal Size?

After around four to five weeks beyond the conclusion of the heat cycle, your dog’s nipples should be back to their standard size. Once your dog’s hormones balance, the nipples will return to normal. The timeframe to return to normal size can vary, but generally, it’s about one month.

When To Contact a Veterinarian

On the other hand, if alarming symptoms accompany the enlarged nipple—call the vet immediately. Here is what to look out for:

  • Loss of appetite
  • Fever
  • Scratching excessively or even biting the nipples
  • Pain in the surrounding areas, especially the mammary gland itself
  • Wounds in the surrounding areas and the mammary gland itself
  • Fluid or discharge from the nipples
  • Masses and lumps beneath the skin

If your dog appears fine, but the nipple swelling and enlargement remain even after a few weeks, visit your veterinarian. Perhaps the heat cycle wasn’t the only reason for the swelling. Potential problems could include infection, false pregnancy, or even an allergic reaction to a product or food.

Other Symptoms of Being in Heat

Below are both physiological and behavioral that can happen while your dog is in heat:

1. Roaming

Your dog may roam outside its yard searching for a potential mate. Moreover, while she’s out, she will seek attention from male dogs.

2. Unusually aggressive behavior

Your dog may withdraw and be less social with people; she may try to pick fights with other in-tact females.

3. Flagging

You’ll notice that you will keep her tail up and angle her behind towards males showing them that she is ready to mate.

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4. Swollen vulva lips/bloody discharge

Blood and discharge can vary in amounts when your dog is in heat. The vulva also becomes swollen, which may lead to licking.

5. Frequent licking

Dogs tend to incessantly lick their genitals when in heat to ease frustration and clean the area from discharge.  

6. Frequent urination

Your dog will begin urinating more frequently to spread her pheromones.

Canine Heat Cycle | The dog Period!

Frequently Asked Questions

Below are the answers to the most commonly asked questions concerning the enlargement of a dog’s nipples while in heat:

How does a dog change after the first heat?

It varies depending on the dog. A dog may become more fussy and grumpy with its owner; other times, it may become more affectionate. When it comes to food, a dog may get hungrier, or they may eat less food during this time.

Are dogs uncomfortable when they’re in heat?

Again, this varies from dog to dog. For example, some dogs become restless while others may feel more tired. Examining your dog’s behavior and selecting the right amount of exercise and rest are essential in keeping your dog comfortable.

How long do a dog’s nipples take to return to the average size after being in heat?

The enlarging and swelling of the nipples should return to normal three to four weeks after they’re no longer in heat.


Final Thoughts

It’s understandable to be concerned about your dog when in heat, especially if it’s their first one. Now you know nipple enlargement is normal while your dog is in heat.

Remember that different dogs have different psychological and behavioral responses to being in heat. Some dogs become restless, while others become more tired. It is essential to observe your dog’s behavior and adjust accordingly.

Knowing what to expect and the potential dangers involved in nipple enlargement is crucial to eliminate unwarranted worry and help your dog navigate this time appropriately until it’s over.

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Susan Dorling

I am a pet expert with years of experience working with a variety of animals. From dogs and cats to birds and exotics, I have a deep understanding of their unique needs and behaviors. I am dedicated to helping pet owners provide the best care for their furry friend.