Why Do Male Dogs Have So Many Nipples? Mystery Solved!

Just like female dogs have nipples, male dogs also have nipples. The difference is that in male dogs, their nipples actually serve no purpose!

If you don’t spend much time examining your dog’s body, you will likely be shocked to find small bumps on your male dog’s belly or around the groin area. This can still be a surprise even if you were already aware that male dogs have nipples.

The question remains- Why do male dogs have so many nipples, even though they obviously won’t be needing them for nursing?

Male dogs have nipples for the same reason as human males. During the development stage both sexes start off the same, which means that some characteristics are shared. One of the shared fetus characteristics is the presence of nipples.

Anatomically, male and female dogs are identical in the womb until hormones begin to flow into the fetus, creating differences in sex.

Since the nipples are already there by then, the hormones play their part in the development cycle to develop unique reproductive organs and other significant biological differences.

Nipples in male dogs remain in a rudimentary state and so for a lack of a better word, are useless. Unlike female dogs’ nipples, the nipples of male dogs do not produce milk.

That said, male dogs with nipples have no evolutionary advantage over male pups with no nipples. Today I will help you answer various awkward questions you may have relating to male dog nipples!

How Many Nipples Should A Male Dog Have?

Whether neutered, intact, or spayed, all male dogs have nipples. While most dogs have ten nipples, there are in fact no hard or fast rules for how many nipples a male dog should have.

The number of nipples in a male dog varies depending on the dog’s size and breed. Most boy pups have 8 to 10 nipples.

However, some breeds have up to 12 nipples, while others may have fewer. After all, there are no benefits for male dogs that have more nipples, so it doesn’t really make any difference in terms of development and evolution.

No matter how many nipples your male canine companion has, they will be placed in two rows down the torso of his body. Dog’s nipples typically start from the chest and go down to the groin. However, sometimes nipples will show up in unusual places.

Why Do Boy Dogs Have Multiple Nipples?

Cocker Spaniel lying belly up on sofa

Why do male dogs have multiple nipples? What a funny question.

To answer this properly, let’s look at it this way: Most male mammals, including human males, have nipples. They can even be inverted! That said, it makes perfect sense for male dogs to have multiple nipples just like their female counterparts.

However, the reason why canines have multiple nipples in general remains a mystery, considering the fact that the nipples serve no purpose for males. 

While the exact answer to why male dogs have multiple nipples is yet to be found, evolutionary biologists attribute this to the development stages of embryos.

According to the AKC, all embryos start as androgynous, and nipples develop at the early stage in utero before sex is determined. Once hormones flow into the fetus and gender is solidified, other organs begin to grow depending on the sex of the embryo.

That said, it is a no-brainer to say that the reason male dogs have multiple nipples is because the natural selection process did not weed them out.

Nipples in both male and female dogs run in two parallel lines, from the chest to the groin area, where each pair is named depending on its anatomical location.

For a male dog with ten nipples, each set or pair has a unique name. Here are the names for each set:

  • The inguinal nipples: This is the set located closest to the groin.
  • The cranial abdominal nipples: These two nipples are on your dog’s belly
  • The caudal abdominal nipples: This set is also on the belly.
  • The caudal thoracic nipples: This pair of nipples are on the chest but closer to the abdomen.
  • The cranial thoracic nipples: This is the pair of male dog nipples located on top of the chest.

It is possible for your male canine to miss some of these pairs- or to even have an extra pair. Don’t let this worry you! It is also normal for male dog nipples to stray from exactly where you would expect them to be.

Despite having multiple nipples, male dogs have significantly smaller nipples compared to those of a nursing female. That’s why most dog owners don’t realize that their male canine companions even have nipples!

Some dogs have nipples matching their skin colors, which makes it even harder for pet parents to locate them.

If you have a short-haired dog, you will likely find it easier to notice his nipples. Pet parents whose dogs have long-haired coats may find it harder to locate their male canine nipples unless the nipples are pigmented.

Once again, keep in mind that male dog nipples can either be the same color as his skin or pigmented. Either case, it is completely normal and nothing to worry about.

Do Male Dog Nipples Go Away?

Chihuahua lying on back being silly

No, male dog nipples won’t ever just magically disappear! However, they do tend to get smaller in relative size since they remain in a rudimentary state from birth.

Essentially, nipples are small, round bumps. Because of their small size, some dog owners may think that they disappear as their pet ages.

An intact female dog’s nipples will expand during pregnancy and nursing, then shrink back to their smaller, less noticeable size afterwards.

Male dog nipples can’t disappear, nor can your dog gain new nipples with age.

Can Dogs’ Nipples Get Infected?

As seemingly benign and useless as male dog nipples are, it does not mean that they should be ignored altogether. I regularly check the nipples of all three of my male dogs to note any new changes or developments.

Not the most glamorous job, I admit, but it’s an important one nonetheless.

While male dog nipples are mostly trouble-free, in rare cases they can be the source of health issues.

For instance, it is possible for male canines to develop mammary gland tumors. If this has occurred, you will likely notice abnormal changes in the appearance of the nipple, or the existence of a lump underneath it.

Whenever you notice any changes in the nipples of your male canine companions, make an appointment with your vet immediately to have them checked out.

If the nipples of a male dog are bombarded with bacteria as a result of dirt building up, they can get mastitis.

Mastitis is essentially the inflammation of the mammary glands most commonly brought on by a bacterial infection that has travelled through the teat. Mastitis can otherwise also be caused by trauma to the nipples.

The condition can be fatal if it goes unaddressed. For this reason, you should consult with your vet immediately should you notice any indications of possible infection.

If the nipple of your male dog is infected, the dog will show signs of discomfort or pain.

Keep an eye on the following:

Changes In Nipple Size

Checking a dog's belly and nipples

Any changes to your dog’s nipple size should be a cause of concern.

Swollen male dog nipples can be a sign of mastitis or testicular cancer. Testicular cancer is more common in intact dogs, but can also occur in neutered dogs.

If you notice any changes in your dog’s nipples’ sizes, check for other signs such as a swollen belly, anemia, hair loss, extreme weight loss, loss in appetite, and diarrhea.

These can be signs that something is dramatically wrong. Whether you note other signs or not, go to a vet for an examination and to form a treatment plan.

Change In Nipple Color

It is very typical for your dog’s nipple to change in color as it ages.

While a change in color is very normal when it is gradual throughout the years, a sudden discoloration, especially in young dogs, may be a sign of infection and mastitis. Remember, while mastitis is not as common in male dogs, it doesn’t mean that it can’t occur.

Nipple Discharge:

Male dog nipples are non-functional, so they should not produce anything at any time. If they do, it is a clear sign of infection. If you notice anything coming from the nipples of your male dog, consult a vet ASAP.

Along with the above visual signs, if your dog displays any of the following symptoms it is highly likely that something is wrong with their nipples:

Male dogs whose nipples are infected can also either show unusual amounts of affection or become overly aggressive.

That said, whenever you feel bumps on your pup’s chest or belly, don’t always assume that it is the nipples!

It can be easy to mistake a tick for a nipple as well, especially if you do not look carefully. Therefore, if you see or feel anything out of the ordinary at any time, pay attention and clearly establish what it is exactly!

How Do I Know If My Dog’s Nipples Are Infected?

The most common way to tell if the nipples of your male dog are infected is the existence of swollen and discolored nipples. An experienced vet can tell you with certainty whether your dog’s nipples are indeed compromised.

To know when you should call a vet, make checking your dog’s nipples part of a normal routine so that you can notice any changes (even small ones) immediately.

Keep an eye out for the following:

Enlargement: Increases in nipple size can be a clear sign of testicular cancer or mastitis.

Discharge: While this seldom happens, the nipples of your male canine companion can start secreting substances. Since we know by now that male dog nipples don’t normally have this function, this is a problem that needs to be addressed immediately.

Lumps: If you feel like there are lumps beneath the nipples of your male pup, it can be a sign of an underlying issue. In most cases, swollen nodes are a sign of mammary gland tumors, which thankfully is rare.

What Does It Mean When A Male Dog’s Nipples Are Swollen?

Staffordshire Bull Terrier Cross shaved belly after surgery

The nipples of a male dog should never show swelling under normal circumstances.

All the same, there are many reasons that can cause your male dog’s nipples to become enlarged. Here are various factors other than mastitis and testicular cancer that can make your dog’s nipples swell:


Just like other mammals, nipples are one of the most sensitive spots for a dog as well. Therefore, swollen male dog nipples may simply mean that the nipples are or have been irritated.

Before you assume that your pooch has a severe infection, think about what he has been doing recently. There are chances that the nipples were rubbed inadvertently either through their actions or by the environment, and as a result have now become red, swollen and itchy.

Stomach Pain

Surprisingly, abdominal pain can cause the nipples to swell. To check whether your dog’s stomach is feeling painful, apply reasonable pressure on its belly and see the reaction that it generates.

Mammary Tumors

Enlarged male dog nipples can be a sign that your companion is battling mammary tumors. Read more about them here.


Anemia is another possible cause of nipple swelling in male dogs. An easy way to check if your dog is suffering from anemia or blood circulation issues is by seeing if the color of its gums has changed.

Healthy blood circulation is indicated by bright, pink gums, while pale, white gums show that there may be an underlying issue that needs to be checked out.

If you are suspicious that one of the above reasons has caused the nipples of your male dog to swell, call your vet to devise a solution.

Black Spots On Male Dog Nipples: What Are They?

Inverted nipple in dogs

It can be quite normal for male dogs to have black spots on their nipples. Wax can sometimes build up around the area, trapping dirt and oils and becoming darker over time. Sometimes these can be hard to remove, but it is a relatively harmless phenomenon.

Male dogs are also more susceptible to experiencing overactive sebaceous glands. These glands are situated within the hair follicles surrounding the follicles. If a dog is not washed with enough frequency, these can release brown substances and become infected.

The deposition of these substances on the skin results in the formation of black spots. Keep in mind that there is no specific treatment for this problem other than giving your dog a good scrub from time to time to help remove dirt and oils!

Other possibilities for black spots on the belly of a male dog can involve the existence of fleas and their excretions (AKA ‘flea dirt’).

Bathing your pup with a medicated shampoo (careful not to get it in the eyes!) and treating it with a preventative like Frontline or Seresto will help to kill the fleas and remove the black spots.

Consult your vet in case if you notice the black spots on your dog’s nipples keep changing in appearance and size. This can be a more serious sign and can indicate the development of skin or mammary gland cancer.

In Conclusion

So, why do male dogs have so many nipples?

After reading through this article, you will have learnt that male dogs have such a large number of nipples not because they are of any use, but simply because nipples are one of the earlier structures that are developed in utero- even before sex has been decided!

Precisely for this reason, male and female dogs commonly have the same number of nipples. And while female dogs make good use of them when they become mothers, for males they are simply an (utterly unnecessary) afterthought.

It is not unusual for male dogs to have 5 or 6 pairs of nipples (10-12 in total). These can appear simply as little bumps on the dog’s skin, forming a line from the chest down to the groin area.

However, just because they are useless does not mean that you should ignore them as a dog owner. This is because it is still possible for male dog nipples to become infected through a condition called mastitis.

If you notice any sudden changes in size or color, or if your male canine begins to leak at its nipples (something that shouldn’t ever happen), it’s time to go to the vet as soon as you can to get it checked out. Doing so can be life-saving for your pup!

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