Nipples on Male Guinea Pigs: Do Male Guinea Pigs Have Nipples?

Beautiful young woman looking for nipples on her male guinea pig

While handling your guinea pig, you might discover bump-like structures on your guinea pig’s stomach, during belly rubs. This might get you “do male guinea pigs have nipples?”

Nipples on male guinea pigs.

Weird! Why would male guinea pigs have nipples? Female guinea pigs need nipples to feed their babies if they ever have a litter. But why would male guinea pigs have nipples? Let’s find out!

Have you ever felt your male guinea pig’s nipples before? If not, grab your guinea pig unless he is asleep and check out his nipples on the belly. This would make it less weird. Would it?

Do Male Guinea Pigs Have Nipples?

Yes, like female guinea pigs, male guinea pigs also have two nipples. While male guinea pigs don’t need them to feed their offspring, male guinea pigs are no different from most mammals (including humans) in that both sexes have nipples.

What Do Male Guinea Pig’s Nipples Look Like?

Both male (boar) and female (sow) guinea pigs have nipples but male guinea pigs’ nipples are smaller in size. Most guinea pig owners only notice nipples on their boars, when they are carefully looking for mites in their guinea pigs.

Male guinea pigs’ nipples are smaller in size; many guinea pig owners who do not know that male guinea pigs have nipples, think of them as mites. Male guinea pigs’ nipples are surrounded by a small circular bald spot with a diameter of around one-third to one-fourth of a centimeter.

Guinea pig nipples are located on their lower stomachs, right above the area where their hind legs connect to their bodies.

As far as the color of the guinea pigs’ nipples is concerned, it varies depending on the skin color and markings.

Is It Normal for Male Guinea Pigs to Have Nipples?

Yes, it is completely normal for male guinea pigs to have nipples. There is no reason for you to be concerned if this is the first time that you have noticed nipples on your boar.

Male members of the specie having nipples is not peculiar to guinea pigs—both sexes of almost all mammals, including humans, have nipples. However, where females use their nipples to feed their young ones after birth, male guinea pigs’ nipples are non-functional. Just like nipples on men, boy guinea pigs’ nipples serve no purpose.

Why Do Male Guinea Pigs Have Nipples?

Knowing that your male guinea pigs have nipples that serve no purpose, other than making novice guinea pig owners think for a moment that their piggies have mites, you may wonder: why do male guinea pigs have nipples?

Well, when the guinea pig gets pregnant and the process of development of baby guinea pigs is initiated, embryos of both male and female guinea pigs look like. All guinea pigs develop nipples in their mother’s womb, before the determination of sex and release of sex hormones. Where the sex hormones produced in female guinea pigs trigger the development of mammary glands, the release of testosterone in male guinea pigs leads to the immediate inhibition of the development of mammary glands. With no developed mammary glands behind them, male guinea pig nipples are completely non-functional.

Do Male Guinea Pigs’ Nipples Work?

No, male guinea pigs’ nipples are non-functional—they do not lactate—just like men’s nipples. Guinea pigs have nipples but they do not have developed mammary glands.

While all guinea pigs get their nipples before the sex of their respective embryos is determined, the development of mammary glands is only decided after the release of sex hormones. Where the release of the male sex hormone (testosterone) inhibits the development of mammary glands, the release of the female sex hormone (estrogen) triggers the development of mammary glands in female guinea pigs. 

How Many Nipples Do Male Guinea Pigs Have?

All guinea pigs—both male and female, usually have two nipples. That said, it is not too uncommon for guinea pigs to have a vestigial third nipple. On rare occasions, guinea pigs may even have four nipples. On long-haired guinea pigs such as Sheltie guinea pigs, Texel guinea pigs, etc., you may never notice nipples as they will be well hidden under all that fluff.  

Extra nipples are almost always non-functional in both male and female guinea pigs.

The third and even fourth nipple is nothing to worry about unless you are confusing some lump or cyst with a nipple. So, next time you take your guinea pig to a vet, ask them to take a look at that third nipple and rule out the probability of a tumor, cyst, etc. 

Black and White Roan Guinea pig with four nipples encircled
image by RodentsRus
White guinea pig with three nipples
image by Kim37040

Can Male Guinea Pigs get Nipples-Related Health Issues?

Yes, just like female guinea pigs’ nipples, the nipples of male guinea pigs are also susceptible to a series of health issues. Below we have briefly discussed each nipple issue.

1. Mammary Gland Tumors in Male Guinea Pigs

One might think that as male guinea pigs do not develop mammary glands, they might not be susceptible to mammary gland tumors, but it is not the case. In fact, male guinea pigs are more susceptible to mammary gland tumors. According to PetMD, these mammary gland tumors are not always cancerous—they are benign fibroadenoma. That said, about 30% to 75% of the mammary gland tumors in guinea pigs are malignant fibro adenocarcinoma, which is fairly aggressive and if not diagnosed and treated at an early stage, these can metastasize, invade local tissue and reach up to lungs. 

Mammary gland tumors usually cause swelling of guinea pig nipples or just behind them. Besides swelling, there could also be either clear or bloody discharge seeping out of the swollen glands.

2. Sebaceous Cysts

Like female guinea pigs, male guinea pigs are also susceptible to sebaceous cysts.

Sebaceous cysts are usually benign growths right under the skin. When guinea pigs develop cysts on their lower abdomen in the nipular area, guinea pig owners tend to confuse them would swollen or enlarged nipples. They are usually painless and do not need immediate intervention unless they burst or your guinea pigs seem to be picking at them.

If your guinea pig has been scratching or biting at the cyst, be careful, as an open cyst could make guinea pigs vulnerable to infections.

3. Bacterial Infection

If male guinea pigs experience an injury on their nipples, they could become susceptible to a bacterial infection, which could lead to swelling, bleeding, and extreme pain. Guinea pigs might get such injuries during their fights with other guinea pigs.

If you notice swelling in the nipular in your male or female guinea pigs, you should observe them carefully and note if they exhibit any other changes. If they seem to be in pain, you may want to take them to a cavy savvy vet immediately, otherwise, you can observe them for a while, and if the swelling does not go away on its own, visit the vet.

Can You Determine Guinea Pig Gender Based on Nipples?

Guinea pig nipples are not gender-specific. Both male and female guinea pigs have nipples, so taking a look at nipples alone would not be enough to make a right guess about the gender of the guinea pigs. However, given that female guinea pigs’ nipples are quite larger than their male counterparts, it could be a good point to start.

Besides guinea pigs’ nipples, you might also want to weigh them as male guinea pigs are usually bigger than their female counterparts.

Wrapping It Up

All guinea pigs, regardless of their gender, have two nipples on their lower abdomen, right above the area where their legs are connected to their bodies. Though boars tend to have smaller nipples as compared to sows, nipples alone are not enough to determine their gender.

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