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Why does my dog have a lump, discharge, and milk, but isn't pregnant?

Updated On September 23rd, 2025

Pet's info: Dog | Chihuahua | Female | unspayed | 10 lbs

My dog has a large lump that came up on her lower abdomen but is growing bigger today she seems constipated straining to have bowl movement and brown discharge from her vagina also her nipples are filling with milk but she is not pregnant

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2 Answers

Most Helpful Answer

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Answered By Rebeccah Wood

Licensed Veterinary Technician, Registered Laboratory Animal Technologist

Published on July 31st, 2017

Hello there! It looks like Princess has a mammary gland problem. What is causing the swelling should be determined at the vet's office. It could be mastitis (an infection of the mammary gland), a cyst (a fluid filled sac), or possibly mammary cancer. At the vet, they will give Princess a complete physical exam, and most likely they will take a small sample of cells from the mass with a small needle to look at under the microscope. This is called a fine needle aspirate, or FNA. The FNA will help the vet determine the cause of the mass and decide it's treatment. An infection may require antibiotics, a cyst may require regular draining, and a tumor may require surgical removal. Mammary tumors in unspayed dogs have the potential of being malignant (the kind of cancer that multiplies and spreads), so they may want to biopsy the mass to rule this out, should it be removed. The brown discharge and milk production may be from a condition called false pregnancy. This occurs when the body is responding as if it has puppies, but it in fact does now. This usually occurs soon after a heat cycle. It is also possible that she has an infection in the uterus, called pyometra, which can also cause abnormal discharge. This also requires a visit to the vet as it could be life threatening. I am suspicious of this due to her straining to go to have a bowel movement, as an enlarged, infected uterus can put pressure on the colon and make a dog feel like they have to go. You should make an appointment with your vet as soon as possible to have Princess checked out. Good luck, and I hope she feels better soon!

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    Answered By Cara, DVM, cVMA

    Veterinarian

    Published on

    I would take Princess to your veterinarian. She may have a mammary infection called mastitis or a mass that is causing the lump on her abdomen, both of which could be serious. I would also be concerned about the vaginal discharge if she is not pregnant it could be a sign of pyometra, which can be a life-threatening uterine infection.

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