why puppies nipples big swollen

A Puppy’s Swollen Nipples (6 Possibilities + Related Issues)

Both male and female puppies have nipples, but is it only female puppies that may have issues with swollen nipples?

If your puppy has swollen nipples, should you worry?

How Many Nipples are Normal?

Your puppy can have between six and ten nipples – an odd number is possible. The nipples may not be symmetrically placed and can appear on the legs as well as the tummy.

If you notice a lump inside your puppy’s leg, check the opposite leg for a match.

If there is, your puppy has odd nipple placement, if you don’t have a matching pair, it may still be nipple in a strange position, but it is worth having your vet confirm this.

Why Does Your Puppy Have Swollen Nipples?

Possible causes of swollen nipples are:

  • Going into heat.
  • Pregnancy.
  • Mammary gland cancer.
  • Cysts.
  • Mastitis.

1. Going Into Heat

Unless you neuter your female puppy before six months, your puppy will go into heat. Part of the hormonal changes in this process can cause the nipples to swell.

The swollen nipples indicate the start (a few days before) and end of the heat.

Between heats, your puppy’s nipples will return to normal.

A discharge from the nipples is not normal and may indicate an infection. If your puppy’s nipples swell and there is a discharge, schedule a visit to the vet.

The first heat arrives around the six-month mark, and you can then expect further heats approximately six to seven months apart.

During your puppy’s season (sixteen to eighteen days, but it can be four weeks), you need to keep your puppy indoors and away from other dogs to avoid an unwanted litter.

After spaying your puppy, you don’t need to worry about her becoming fertile.

You don’t need to wait for her first heat to neuter your puppy.

2. Pregnancy

If you choose to breed with your puppy, it is best to wait until she matures and is at least 18 months and preferably over two years.

Swollen nipples are one of the first signs of pregnancy in a female dog, and towards the birth, you may notice a milky discharge as she prepares to lactate.

3. False Pregnancy

Your female puppy may have swollen nipples during a false pregnancy.

An intact female puppy may exhibit nesting instincts, adopt toys as pretend puppies, and have swollen nipples after the heat.

You can chat with your vet, but typically a false pregnancy is a phase that will pass and allow your puppy to return to normal.

4. Cancer

Both male and female dogs can develop mammary cancer, but it is more likely in a female dog.

Typically, you expect this disease in older dogs (over six years) rather than puppies. Lumps or swelling in one or more nipples are one of the first noticeable effects of this cancer, and you may see a discharge from the nipples.

Neutering your female puppy before her first heat significantly decreases the cancer risk in later life.

You also gain reduced risk if you spay before the second heat. Spaying after two years puts your puppy at the same level of risk as an intact female dog.

It is rare for a puppy to develop breast cancer, but some breeds (spaniels, dachshunds, and poodles) are at higher risk of later life cancer.

If you notice lumps in the abdomen and your puppy seems ill, it is always worth getting a vet to check your puppy’s health.

5. Cysts

Mammary gland cysts are benign tumors, and both male and female dogs can suffer from these. They result from hormonal changes and are more common in unspayed female dogs.

Typically, these are an issue in adult life rather than a puppy, but it is possible.

The symptoms are similar to cancer, but these tumors are benign; your vet will advise if it is best to leave them alone or remove them to prevent infection.

6. Mastitis

Mastitis is a bacterial infection and can be fatal.

Both male and female puppies can get infected glands, but it is more likely in a female puppy after pregnancy or during a false pregnancy.

If you see a discharge from your puppy’s nipples (male, female, and neutered), take your puppy to the vet.

The risk to your puppy is from septic shock, and prompt medical attention is almost always successful in treating your puppy.

Why Are My Puppy’s Nipples Black?

Your puppy’s nipples may move from pink to black because of:

  • Color changes as it matures.
  • Pregnancy.
  • Dirt sticking to the nipples.
  • Dog acne – shows as black spots.
  • Flea dirt.
  • Reaction to sunlight.

Standard nipple color ranges from pink to black and typically matches your puppy’s coloration.

Your puppy’s coat can change color dramatically as it matures, and color-changing nipples may be part of the process.

If your puppy has had a season and escaped your yard, or if you adopt a stray (female) puppy, you may have a pregnant puppy on your hand.

The nipples change color to black or red because of changing hormones.

If your puppy lies on the dirty ground, its nipples and belly may get messy. The dirt is more likely to stick to the nipples because the nipples produce a waxy secretion to keep the skin supple and healthy.

A gentle wipe with an oily (olive oil) cloth or puppy cleaning wipes will restore your puppy’s nipples to their original pink.

Acne is the result of blocked pores – just like human teenagers. These blackheads may appear on and around the nipples.

These swollen cysts may resemble a tumor, so get your vet to give your puppy a health check.

Although you don’t need to clean your puppy’s nipples, if the acne is causing your puppy to bite and lick excessively, you may want to act.

Don’t use human lotions and creams – your puppy’s skin PH is different from yours. Your vet can recommend puppy-safe cleaners, or you can wash with olive oil to remove dirt and retain moisture.

Fleas suck blood, and when they poop, they leave dark spots. These spots appear all over your puppy’s body, so look all over your puppy and check its bedding.

If you see evidence of fleas, you want to treat the puppy and your house.

Dog fleas don’t live on humans, but the bites are unpleasant, and the eggs may remain in soft furnishings, ready to reinfect your puppy.

Modern flea treatments are given orally (tablets) or topically (drops on the skin) every month to keep your puppy in a parasite-free zone.

Your vet is the best person to ask about parasite treatment because different geographical areas and seasons have various issues.

Finally, your puppy may have black or brown sunspots on its nipples if it likes to sunbathe on its back.

You don’t need to worry about flat spots, but if they start to change shape or bleed, have a word with your vet.

If your puppy is getting enough sun exposure to tan, you may consider applying a puppy-safe sunblock.

What About Red Nipples?

Red nipples can result from the exact causes of black nipples but may also indicate an allergic reaction.

The sensitive nipples may become irritated in contact with a carpet cleaner, grass, or other allergens. If your puppy has itchy red nipples, it is time to chat with your vet.

If your puppy’s nipples are red through sunburn, it is time to think about sun protection.

Why Are My Puppy’s Nipples Bleeding?

If your puppy feels itchy – fleas, allergies, or infection – it is possible that your puppy can scratch the surface of the nipple, and these can bleed.

Your puppy can acquire scratches from thorny bushes and other animals.

If the bleeding is superficial when you wipe it with a wet cloth, you don’t need to worry. However, you need to watch for signs of infection – discharge of pus or a bad smell, as this will require medication to clear the infection.

If in doubt about the nature of the bleeding, consult your vet.


Most nipple swelling in female puppies relates to her coming into season, and her nipples will return to normal after she stops being in heat.

Spayed female dogs don’t have this hormonal swelling.

If pregnancy is a possibility, consult your vet for advice.

You need to act if the swelling seems abnormal (male puppies don’t go into heat), have a smelly discharge, or irritate your puppy.

Most puppy issues with swollen nipples are minor and straightforward to treat. Checking the condition of your puppy’s belly and nipples is part of the daily health check of your puppy’s condition.

You will soon know what is typical and what needs attention as your puppy matures.