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Why does my older spayed dog have a swollen nipple with lumps?

Updated On September 23rd, 2025

Pet's info: Dog | Mixed Breed Medium (23 - 60lb) | Female | spayed | 7 years and 8 months old | 50 lbs

Large swollen nipple on female dog aged 7.5. Spayed after 1 heat. 2 large marble sized lumps underneath the skin around it.

3 Answers

Most Helpful Answer

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Answered By Dr. Davis

Veterinarian

Published on August 19th, 2017

These could be mammary tumors even if she was spayed after her first heat. Please take her in for an exam. The veterinarian will feel the lumps and check the nipple. They can do a needle aspirate to see if it is infection or cancer. Breast cancer in dogs can be slow growing and often can be cured with surgery. They may recommend an X-ray to make sure there are no growths in her chest or abdomen before surgery. A biopsy of the lumps will also tell what it is and if it has been completely removed. If there is infection in the nipple area they will put Zephyr on antibiotics. Please have this examined soon so she can get the necessary treatment and be on the road to recovery. Thanks for using Petco Pet Education Center, formerly Petcoach to help you care for Zephyr.

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    Answered By Dr. Melanie, BVSc MS

    Veterinarian

    Published on September 18th, 2017

    Bonnie needs to see a vet for this swollen mammary gland. It is concerning that it has been swollen for three years now. I'm not sure if she is spayed or not, but this swelling could be a mammary tumor. In unspayed dogs, they have a 25% chance of developing mammary tumors, 50% of which are malignant. It could also be a cyst, and she scratched it open leading to the fluid leakage. Even if she is spayed, it's not normal to have such a huge swelling for so long, and it really needs to be diagnosed by a vet to it can be treated. I would take her into the vet first thing tomorrow. I hope this helps!

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    Answered By Dr. Melanie, BVSc MS

    Veterinarian

    Published on January 27th, 2018

    I see that Brandy isn't spayed. When dogs aren't spayed, they are prone to developing mammary tumors. There is a 50% that a mammary tumor can be malignant, and it's concerning that her swollen nipple is getting larger. I would take her into a vet as soon as possible. The vet can diagnose if she does have a mammary tumor, and if she does have one, if it's malignant or not. Malignant tumors will have to be removed surgically. Please take her into a vet this weekend or first thing Monday. Good luck, I hope this helps!

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Related Questions

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My non spaded 10 year old Chihuahua has an enlarged nipple..sometimes it gets small and other days it swells...doesn't seem to hurt her or bother her, I notice it more than she does! I read it could be a clogged milk dud, or even breast cancer for do
Thank you for contacting Boop by Petco with your question about Zoe. Wow, that is quite enlarged. I am concerned that she does have a mammary tumor. Those can be common in dogs who are not spayed. Unfortunately there are no natural remedies for this, and it does require veterinary treatment. You also need to be aware that 50% of these tumors are malignant, so there is a chance it is cancer. The only way to know for sure is to have her seen by a vet to get it diagnosed. The vet can perform a test called a fine needle aspirate on it. To do this, the vet sticks a small needle into the lump to get a sample of its cells, and examines the cells on a slide under a microscope. It's usually painless to the animal, and relatively quick to perform. If paying for a vet is an issue, you can see if your vet accepts payment plans, if there is a low cost clinic in your area, or you can apply for Care Credit online. There is also an organization called Red Rover that give grants for treatment
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Hello. This is probably benign mammary hyperplasia, but you do want to have this looked at, especially if she has been spayed. If she has not been spayed & has never been with a male dog, then this could be related to a false pregnancy. Also, has she been in contact with anyone who is on hormone replacement therapy? Sometimes, this can rub off on a pet & cause mammary enlargement. If no outside cause can be found, then have her spayed if that has not already been done, & submit a biopsy to see exactly what is going on with the tissue. Thanks for using Boop by Petco.
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That could be due to a mastitis (infection of the mammary gland) or possibly the tumor could have turned not benign anymore. This kind of lump/growth needs to be ideally assessed by your veterinarian to have a definitive and specific answer. Usually there are two ways your vet can do that a part from examining it directly during physical examination. A biopsy can be taken under local or general anesthetic, otherwise a smaller sample through a fine needle can be aspirated (this technique is called FNA= fine needle aspiration). The biopsy usually give definitive/reliable results. Chest x rays may be needed as well in case of a tumoral growth. Hope this answer was helpful, but please do not hesitate to contact us again on the forum or by requesting a consultation if you have any more questions or to discuss it any further.
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I'm not sure if Dhuli is spayed or not. You say she is sterilized in the beginning of your post, but then at the end, you say she went into heat. If she was spayed, she could not go into heat. Intact dogs are prone to mammary tumors, and this may be causing her issues. These lumps look terrible, and I would be very afraid she could have malignant mammary tumors. You do need to take her into a vet asap. Best of luck.
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Hi, thanks for using Boop by Petco! There is no way to tell if a lump in the mammary gland is cancer or benign with out a fine needle aspirate (which still may not tell you 100%) or removing the mass and biopsying it. Mammary gland infections are rare. The smaller the mass the more likely it’s benign. Spaying a dog before too many heat cycles has proven to protect against mammary cancer in dogs. I wish you the best!
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