Why Do Dogs Have 9 Nipples? [Mystery Solved!]

By: Mr Nguyen

Theo dõi chúng tôi tại Google News

Both female and male dogs have nipples. Their number most often ranges from 6 to 10 and doesn’t really depend on the dog’s age or breed. What’s more, some dogs have 9 nipples or another odd number, like 7 or 5.

Why does this happen? Vet experts don’t have a clear idea why some dogs have 9 nipples and others don’t. Most likely, the asymmetry of mammal glands is simply a minor birth defect, similar to a supernumerary nipple in humans. What we know is that an odd number of nipples is entirely normal and doesn’t pose any health risks.

Read on to learn why dogs have 9 nipples or more, can a dog grow a nipple, and 5 most common reasons of swollen reasons beyond pregnancy.

Do All Dogs Have The Same Number Of Nipples?

Typically, most dogs have 8 to 10 nipples. Wonder why there are so many?

The main reason dogs have 9 nipples or more is that dogs tend to have a large litter. Unlike humans, who usually have one or two babies simultaneously, dogs can have three to eight puppies at the same time. Naturally, a female dog needs to provide food for all of them, hence a large number of nipples.

Dog’s nipples are located on the dog’s belly and often arranged into symmetrical rows with 4 or 5 nipples on each side. However, veterinary experts agree that it’s pretty common for these numbers to vary from dog to dog. For example, it’s not unusual for some dogs to have only 4 or 6 nipples.

The variations in the number of nipples are completely normal and pose no cause for concern. They don’t depend on the dog’s breed, age, or health. However, smaller dogs like Chihuahuas might have fewer nipples than larger dogs like American Bulldogs simply because their bodies are smaller, and biologically, they don’t have space for a large litter.

A brown dog with visible nipples lying on the back on a red carpet
Normally, most dogs have 6-10 nipples. However, some dogs have 9 nipples. An odd number of nipples is completely normal and doesn’t pose any health risks.

Why Do Dogs Have An Odd Number Of Nipples?

Though it might seem somewhat unnatural, not all dogs’ nipples come in pairs.

Some dogs have 9 nipples, with five nipples located in one row and four nipples in the other. Others have 7 teats arranged in a row of four and three.

Why do dogs have 9 nipples, and should you be concerned if your dog has an odd number of teats?

Vets say – not at all.

In fact, asymmetrical mammary glands are a normal anatomical variant in dogs. Any uneven variation in the number of dog nipples, whether it’s 9, 7, 5, or 3, is never a reason for medical concern and doesn’t require treatment.

Interestingly, there’s no specific reason why some dogs are born with an odd number of nipples. The development of an extra teat in your dog is mostly random and might simply signify a minor birth defect, just like a supernumerary nipple in humans.

Do Male Dogs Have Nipples?

Just like human males, male dogs have nipples. However, unlike female dogs, their teats are not functioning. They cannot produce milk and simply point to the location of their mammary glands.

Similarly to female dogs, the number of male nipples can vary from one male dog to another – any number from 3 to 10+ is healthy.

There’s not much difference in the normal nipples of both males and females. For the most part, they look and feel like dots or small bumps. The color can vary – black, pink, beige, or a combination of these are all considered normal.

Unlike female teats during heat or pregnancy, male nipples do not significantly change in size throughout life. If you notice your male’s nipples getting swollen or red or feel a palpable lump under them, call your vet to rule out potential medical problems.

A small puppy waiting to get nursed by a female dog with 9 nipples
Both female and male dogs have nipples. Though, the teats of the male aren’t functional and cannot produce milk. They also don’t change size throughout life, and any visible changes in appearance warrant a call to a vet.

Can Dogs Grow Extra Nipples?

If you’ve given your pup an unusually short haircut and suddenly noticed an extra nipple even though it never seemed to be there, it probably left you wondering: Can dogs grow extra nipples?

The answer is – no.

Dogs cannot grow extra nipples, even when their hormones spike up during heat or pregnancy. This is because nipple formation is a part of embryonic development in utero.

The most probable explanation why many pet owners think their pups grow extra nipples is because many dogs have thick fur, making nipples less visible and palpable.

There must be another medical explanation if you’re absolutely sure that your dog didn’t have a nipple in that particular spot. What looks like a new nipple might actually be a tick, a bug bite, or a malformation. In this case, it’s best to call your vet for medical advice ASAP.

Can A Dog’s Nipples Swell Even If Not Pregnant?

Female dog nipples generally enlarge and swell when your dog is expecting. This is one of the ways your dog’s body is preparing for milk production to feed the litter.

But what if you notice your dog’s nipples are swollen when she is not pregnant?

Here are the five most common medical reasons why your dog’s nipples enlarge and swell.


Also known as a false pregnancy, pseudopregnancy occurs when an unspayed female dog displays signs of physical pregnancy without actually being pregnant.

In the book Dog breeding, whelping, and puppy care, veterinarian Gary England explains pseudopregnancy as “a primitive mechanism to nurture other pups in the dog pack when pro-oestrus/oestrus occurred once a year, i.e., when the pack exhibited synchronized breeding.”

A female dog with a false pregnancy will show elevated prolactin levels, enlarged and swollen nipples, and can eventually start lactating.

Mild cases of pseudopregnancy don’t require treatment, and the symptoms will disappear within 10-30 days.


Mastitis is the inflammation of the mammary glands often caused by bacterial infection. While it’s most likely to occur in female nursing dogs who have recently whelped a litter, it can also occur in dogs who experienced pseudopregnancy after their last heat.

Siberian Husky mother nursing little puppies
The main reason dogs have 9 nipples or more is that dogs tend to have a large litter and need to provide food for all of them.

Mammary tumor

Swollen nipples with palpable lumps can be a sign of mammary neoplasia. Since around 50% of tumors are malignant, it’s essential to be on the lookout and call your vet whenever you notice abnormal swelling or lump in the areas of nipples and breasts.

Mammary hyperplasia

Hyperplasia is when the mammary glands, including nipples, enlarge and develop lumps. The symptoms of mammary hyperplasia, such as swollen nipples, can come and go and largely depend on the unspayed female dog’s estrus cycle. This is because mammary hyperplasia develops due to continuous exposure to progesterone – the primary hormone responsible for breast growth that spikes during the luteal phase of the estrous cycle.


Any trauma or injury to the nipple or surrounding area increases the risk of bacteria penetrating your dog’s mammary glands. This, in turn, will trigger inflammation processes, leading to swelling and redness.

Do A Dog’s Nipples Get Bigger Before A Heat Cycle?

As a rule, adult dogs’ nipples don’t get bigger before a heat cycle. The enlargement is more likely to occur during the heat or right after it as a sign of elevated progesterone.

The exception to this rule is puberty. As puberty approaches, young female dogs show elevated levels of estrogens. These hormones lead to the development of vulva and mammary glands and enlarged nipples.

Có thể bạn thích