Dog Discoveries

I am Your Dog’s Nipples


Have you ever wondered whether male dogs have nipples? Regardless if your dog is male or female, spayed or neutered, he or she will have several nipples along the abdomen. The function of dog nipples is quite obvious, they are there in case there’s ever a need to feed a hungry litter of puppies, but something worth pondering is why do male dogs have nipples too? Turns out there’s likely an evolutionary reason why male dogs have nipples too, and no, it obviously has nothing to do with helping mother dogs deliver milk as last time we checked, male dogs do not produce any! So today’s spot of honor is deserved to the dog’s nipples, so let’s see what they have to say and if they can help us solve the puzzle on those nipples in male dogs!

dog nipplesIntroducing Your Dog’s Nipples

Hello, its your dog’s nipples talking! Of course, you may have noticed us many times when you give your dog those so much craved belly rubs! We are neatly distributed side-by side starting from below your dog’s chest all the way to the groin area near the back of the dog’s legs.

How many nipples do dogs have? Well, it really depends on how large or small your dog is. For small dogs, there are on average eight of us, while in larger dogs we are ten.

Did you know that depending on our location, we have different names?

Here’s a brief guide for your reference: the first two of us starting from your dog’s chest area are known as cranial thoracic nipples, the following two are called caudal thoracic nipples, now moving towards the abdomen, the next two are known as cranial abdominal nipples, next two are the caudal abdominal nipples, and finally, you’ll have two inguinal nipples as shown in the picture on the left.

We are also known as mammary glands, because, yes, we are ultimately glands if you want to get technical. Actually, if you want to be really nit-picky, consider that we are modified sweat glands. At least, that’s what  Dr. Justin Lee in the book: ” It’s a Dog’s Life…but It’s Your Carpet” says about us.  Only difference is that instead of secreting sweat we secrete milk.

Welcome to the Milk Bar!nursing

Of course, you already know that we are there to deliver milk to hungry puppies, but of course, our main functionality goes down the drain if your dog is spayed or if you have a male dog. But for the sake of giving us a job to do, a least for this article, let’s pretend we are on an intact female dogs that is pregnant.

When mother dog gives birth, we start swelling and secreting milk from several small ducts distributed around our tips. Then, once puppies no longer depend on milk, we shrink back to our normal size. How convenient is that?

When Things Go Wrong

When everything goes well, we look and feel normal with no obvious swellings, masses or lumps. When pups are nursing and we do our job well, we keep the pups happy and well nourished.

When weaning time is around the corner, puppies start developing sharp teeth and “ouch!” do they hurt us! This will expedite the weaning process as poor mother dog becomes more and more reluctant to nurse (and who can blame her!)

When this happens,  hungry pups will start looking for alternate forms of nourishment under the form of “puppy mush” offered by the breeders and the weaning process can begin. While we are generally healthy, as with any structure or body part, we are prone to have our own sets of problems and some of these nipple problems can affect male dogs too!

False Pregnancy

Something worth mentioning is that in female dogs who weren’t spayed, we can get swollen and even produce milk even when the dog didn’t mate. How can this be physically possible? This is known as a “false pregnancy” and trust us, it may look like the real thing. While this isn’t really a medical condition or disease, it’s something worthy of mentioning. Here’s brief overview of what happens: after the heat cycle is over, hormonal changes take place whether the female dogs were bred or not. The dog’s body therefore gets confused thinking that the dog is pregnant when she is not, therefore causing several physical and behavior changes as seen in real pregnancies. Fortunately, the effect is short lived and subsides once the dog’s body realizes that there is no puppy stimulation going on. False pregnancies can be totally avoided by spaying.

Bacterial Infectionsmastitis

We can be prone to infections which is known as mastitis. We often get this when puppies are nursing and they scratch us with their sharp nails.

Another way is through abrasion as seen when we’re closer to the ground in short dogs with short legs. When bacteria enters us causing an infection, we get swollen, hot, painful and may have a discharge. Breeders should step in at this point and prevent pups from nursing on us when we’re infected as the milk can make the pups sick.

Crying puppies or puppies that appear sick or are dying should raise a red flag that something is possibly wrong with us, warns Dr. Douglas Brum. Your best bet is to keep a good eye on us when your pups are nursing!

Milk Production Problems

While we are known for producing milk, sometimes things can go wrong in the milk production department. We may fail to produce milk or we may be unable to excrete it. When this happens it’s known as agalactia and it can be due to problems with us  or it could be mother dog hasn’t been fed correctly or she may be suffering from some type of systemic illness. On the opposite side of the spectrum, sometimes we may produce too much milk, which is known as galactorrhea. This seems to occur mostly during false pregnancies.

A mammary tumor in dog
A mammary tumor in dog

Mammary Gland Cancer

As women, dogs can get breast cancer too. Fortunately, we are not that much affected when dogs are spayed. According to veterinarian Race Foster, dogs spayed prior to their first heat have only a 0.05 percent risk of mammary cancer; whereas spaying after the first heat raises the risks to 8 percent and spaying after the second year raises them to 26 percent.

While dogs can’t do breast self exams, dog owners can take up the task by checking us out every now and then and seeing the vet promptly if  any masses or abnormal swellings are noticed.

The masses may range from pea gravel size to tennis ball size or larger. Fortunately not all masses are necessarily cancerous, several can be benign. The only way to know for sure whether a dog’s mass is malignant or benign is through a biopsy.

The Mystery Behind Male Dog Nipples

male dog nipples

So now comes the answer you have been long waiting for: what in the world are we doing on a male dog? It’s not like male dogs have puppies, and most importantly, they will never be lactating or nursing a litter of puppies, so what’s going on? Is it some trick from Mother Nature?

Well, turns out since male dogs will never have to nurse, we remain in what experts explain as a “rudimentary state.” However, we are still there nonetheless, so we still need an answer to the question: Why do male dogs have nipples? Turns out, it’s likely a matter of economy.

You see, when puppies are just embryos in mother dog’s womb, both female and male puppies are exactly the same, with no main distinguishing features. As they develop therefore, both male and female have nipples. It’s almost as if Mother Nature used the same cookie cutter mold for the sake of economy.

Afterward, when hormones start kicking in, the first distinguishing features that sets female dogs from males apart are added. If you are interested in the process, it’s known as “sexual differentiation.” So turns out that according to what evolutionary biologists say, there’s likely a lack of  enough adaptive pressure going on to make it worthy to no longer make us appear on a male dog’s chest. Until there’s lack of selection against them, male nipples are therefore here to thrive and stay.

I hope this has helped you understand us better! Best regards,

Your Dog’s Nipples.Dog Pawprint

Disclaimer: this article is not to be used as a substitute for professional veterinary advice. If your dog has a medical problem, see your vet for diagnosis and treatment.



  • It’s a Dog’s Life…but It’s Your Carpet: Everything You Ever Wanted to Know About Your Four-Legged Friend by Justine Dr Lee, Three Rivers Press; 1 edition (April 1, 2008)
  • Pet Place, Mastitis in Dogs, by Dr. Douglas Brum, retrieved from the web on May 9th, 2016
  • Pet Education, Mammary Cancer in Dogs, Drs. Foster & Smith, Inc. by Race Foster, DVM, retrieved from the web on May 9th, 2016


Photo Credits:

  • Mammary tumor in a dog, Joel MillsOwn work Mammary tumor in a fourteen year old Labrador Retriever. The tumor is about eight centimeters in length. It was confirmed to be a carcinoma on histopathology. CC BY-SA 3.0
  • Udder of a Roux du Valais sheep after a healed mastitis, one teat was lost due to the disease, by BullenwächterOwn work, CC BY-SA 3.0

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