Why Are My Guinea Pigs Nipples Sticking Out? Find Out Now

Last updated on April 24th, 2023 at 08:00 am

Guinea pigs are wonderful pets that are very funny and always know how to cheer us up, that’s why we keep them and take care of them.

Caring for guinea pigs involves helping them when they have any injuries or illnesses.

You must be worried when you see the nipples of the guinea pig sticking out and wonder why this is happening.

Why do guinea pigs’ nipples are sticking out?

When guinea pigs nipples look like they are sticking out it may be because they are pregnant or nursing. When the nipples come out, it can also be a sign of health problems such as infections or, in the worst case, cancer.

Therefore, in today’s article, you will learn why the nipples of guinea pigs sticking out, diseases that are associated with enlarged nipples, and similar questions related to this topic.

Why are my guinea pig’s nipples sticking out?

Guinea pig nipples stick out when females are pregnant or nursing, which is completely normal.

But this also happens when your pet has health problems such as tumors, cysts, infections, and inflammations.

So let’s see what can be the cause of this phenomenon in guinea pigs and how to help your pets.

Pregnancy causes nipples to look like they are sticking out

When a female guinea pig is pregnant, her nipples stick out and this is completely normal behavior that should not worry you.

Then the nipples are actually bigger because the mother guinea pig is preparing to give birth and nurse the baby guinea pigs.

When a female is pregnant, it is noticed by the following symptoms:

  • greater appetite for food and water
  • an enlarged stomach which in the seventh week leads to a doubling in their weight
  • separation of the pelvic bones in preparation for new babies
  • the babies are moving in her belly and it can be noticed

Females’ nipples will look like they are sticking out while she is pregnant and that is completely normal, it is only dangerous if after pregnancy they have swelling, the appearance of blue color around them, and inflammation.

Such swellings can be a sign of mastitis, that is, an infection that can be dangerous for them and must be treated.

If the female guinea pigs do not have any swelling when they nurse their babies then everything is fine with their nipples.

Hormonal changes cause nipples to look like they are sticking out

We must emphasize that both male and female guinea pigs have nipples, but the female ones are more noticeable and sometimes appear to stick out.

When a female guinea pig becomes sexually mature, which is about two months into its life, they go through hormonal changes that cause nipples to enlarge.

It is quite normal for female guinea pigs’ nipples to look like they are sticking out when they are sexually mature and this should not worry you as long as the cause of this appearance is not related to an infection or tumor.why are my guinea pigs nipples sticking out

Infections cause the guinea pigs’ nipples to stick out

Infections are very unpleasant and can be a painful condition for your guinea pig and can cause nipple enlargement.

When the nipple comes out, it is simultaneously full of pus and has a red color, all this as a result of infection.

Guinea pigs usually get infections due to an abscess or an injury.

Mastitis causes nipple enlargement

When guinea pigs have nipple inflammation the following symptoms appear:

  • swollen nipples
  • bloody or clotted discharge
  • the color around the nipples turning blue

Mastitis is a bacterial infection that occurs in the milk glands, and the cause can be a scratch or a wound caused by baby guinea pigs, or rather by their teeth.

This infection, if not treated in time, can be very dangerous for the health and life of the guinea pig, because it can lead to death.

When guinea pigs have mastitis it can be noticed by the following signs:

  • dehydration
  • lethargy
  • lack of appetite
  • poor production of breast milk
  • fever

Mastitis can be treated with antibiotics, but the mother guinea pig should not be allowed to nurse her young until she is well.

Nursing It will have to be done by another lactating female or hand-fed milk by the owners.

Another thing to do is to pay attention to hygiene, soft bedding, and a healthy diet until the guinea pig with mastitis recovers.

Lumps and swelling

Lumps and swelling caused by tumors and sebaceous cysts can cause guinea pig nipples to stick out.

Only female guinea pigs can have mastitis, but when it comes to cysts, tumors, and abscesses they can occur in both male and female guinea pigs.

Breast cancer

it appears in both male and female guinea pigs and is manifested by an enlarged nipple, which grows more over time, but usually does not spread to other parts of the body.

Breast cancer most often occurs in older guinea pigs, although it can sometimes occur in younger ones.

It can be removed with surgery, but this is no guarantee that it will not reappear.

Sebaceous Cysts

Sebaceous cysts cause the guinea pig’s nipples are sticking out, but luckily they are benign which means they do not spread throughout the guinea pig’s body.

These painless growths appear mostly under the skin and they can be removed, or they can burst on their own.

If they burst then there is a risk of infection and therefore it should be treated immediately.why are my guinea pigs nipples sticking out

Ovarian cysts cause guinea pigs’ nipples to stick out

When guinea pigs have ovarian cysts it can cause their nipples to start sticking out.

Ovarian cysts appear only in female guinea pigs and it is quite common, that is, 75% of them can get a cyst by the time they reach 4-5 years of their life.

Ovarian cysts are actually pockets of fluid that appear near the ovaries themselves and are the result of a higher amount of the hormone estrogen.

The following symptoms also appear:

  • lethargy
  • aggressive behavior
  • decrease in appetite
  • belly enlargement
  • decrease in fertility
  • hair loss especially in the stomach and sides
  • swelling around the nipples

When guinea pigs have ovarian cysts it may not be noticeable except for the appearance of swelling and enlarged appearance of nipples.

However, if you notice any of the symptoms we have listed, you should take your guinea pig to a vet to be examined, as ovarian cysts can cause uterine cancer.

Two methods are used to treat ovarian cysts:

  • hormone therapy
  • operation

If the hormone therapy does not produce results, then an operation is applied, which can be dangerous for the guinea pig’s life, but it is a permanent way to solve the problem of ovarian cysts.

Are nipples the same in all guinea pigs?

No, nipples are not the same on all guinea pigs.

For example, although both male and female guinea pigs have nipples, the females are almost always larger.

The size and shape of normal nipples do not always have to be the same and they can vary from one guinea pig to another, which should not worry you at all as long as they do not have health problems.

How Many Nipples Do Guinea Pigs Have?

Both male and female guinea pigs have two nipples each.

Sometimes, as a genetic variation, it can happen that a female guinea pig has three nipples, but this is a very rare occurrence.

In any case, even if there are three nipples, only two nipples will always function, the third will be without any function.

Read more: Why Does A Guinea Pig Not Let You Touch Its Belly?


When guinea pigs have enlarged nipples that look like they are sticking out it can be a sign that they are pregnant, or it happens when they are nursing their babies.

Enlarged nipples appear when females become sexually mature and this happens after two months of their life and is completely normal.

When their nipples are swollen or have a blue color around them it can be a sign of problems and infections such as mastitis and must be treated.

Other problems that cause sticking-out nipples can be cysts and tumors in female guinea pigs which must be treated immediately.

Finally, whenever you notice that their nipples look like they’re sticking out, it’s best to get them checked out by a vet to see if everything is okay or if it’s a sign of an infection or disease.

Read more: Can Guinea Pigs Have Down Syndrome? All You Need To Know