Why Do Female Dogs Nipples Get Bigger?

Reviewed By Kim •  Updated: 10/10/22 •  3 min read
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Why Do Female Dogs Nipples Get Bigger?

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When female dogs give birth to their puppies, the dogs’ nipples swell and produce milk. The milk feeds the puppies through their first weeks of life. The milk is produced by mammary glands that become larger even during pregnancy in preparation for the puppies.

But what if a female dog’s not pregnant and her nipples become larger? There are several reasons that could cause this condition. We’ve put together information about the top causes of a female dog’s nipples getting bigger. Let’s get started!

Possible Causes of a Female Dog’s Nipples Getting Bigger

Here are some of the most common causes of swollen, larger nipples in female dogs:

Mastitis

Mastitis is a common condition that can begin in mother dogs who are nursing their puppies. Mastitis is an infection of the mammary glands and nipples that can be quite uncomfortable and painful.

The infection causes the nipples to become swollen and painful to the touch. The condition may also cause the mother’s milk to become toxic in the infected nipples. And it’s most common during the first week or two after the puppies are born.

Your dog may show additional symptoms, including:

Mastitis is an infection that must be treated by the vet. So, be sure to call the vet right away if your dog shows symptoms of mastitis.

Mammary Gland Tumor

Another common cause of enlarged nipples in female dogs is a mammary gland tumor. With this type of tumor, a mass develops around the dog’s nipples. The mass may be red or purple and may be hard or soft. Eventually, the mass develops into an abscess.

Mammary gland tumors may be malignant or benign, but this can only be determined by a vet.

Heat Cycle

A female dog’s heat cycle (also called the estrus cycle) may also cause the dog’s nipples to enlarge. During the four stages of the heat cycle, a dog’s mammary glands may swell a little bit in preparation for becoming pregnant. However, once the cycle is completed, the nipples should go back to their normal size.

Summing It Up

These are the most common reasons a dog’s nipples may get bigger if she’s not pregnant. If your dog shows any signs of being ill, tumors, or other issues, it’s time to call the vet.

The sooner your dog is treated, the sooner she’ll be feeling better!

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Kim

Kim is a talented author, who loves animals especially dogs. She engaged in writing books and articles relating to animals a decade ago. Kim resides in Chicago with her husband and son. The family is the proud owner of a dog and a parrot (Jack and Lily). Kim wanted more than these two pets, but her husband put his foot down... She often visits elementary schools to talk to the kids about what she learned about pets and how they could learn from them.