Cat Mammary Swelling Explained: Causes Symptoms Treatment

Grace Aug 11, 2026

Feline Mammary Gland Issues

Tumor basocelular canino
Tumor basocelular canino

Feline mammary gland issues can arise due to various causes, including genetics, hormonal imbalances, and environmental factors. Symptoms such as swelling , discharge, or lumps on the breast tissue may indicate underlying problems. Accurate diagnosis and treatment are crucial in preventing complications and improving quality of life for affected ...

The Greenline Vet Clinic
The Greenline Vet Clinic

Normal events in a female cat's life can lead to the swelling of mammary tissue, such as pregnancy and lactation. However, many infections and other conditions which can be life-threatening also create mammary gland enlargement.

Enlargement of one or more Mammary Glands in cats

Tumors of the Skin in Cats Cat Owners Merck Veterinary Manual
Tumors of the Skin in Cats Cat Owners Merck Veterinary Manual

A common cause of mammary gland enlargement in cats is "fibroepithelial hyperplasia," a benign but often dramatic swelling of the mammary glands triggered by hormonal influences, particularly progesterone. This often occurs in young, uncastrated female cats , but can also occur in neutered animals that have been treated with progesterone.

Basics and possible causes A cat's mammary glands are important glands responsible for milk production during lactation. These glands can swell under certain conditions. One of the most common causes of Swelling in the mammary glands is mastitis, an inflammation of the mammary glands that can be caused by bacterial infections.

Skin Cancer In Cats
Skin Cancer In Cats

Dial A Vet, my cat's mammary glands are suddenly very swollen, and I'm ...

Cats can experience swelling of the mammary glands due to several reasons, including infections, hormonal imbalances, or possibly a more severe underlying issue such as a tumor. It is not usually normal for a cat to display sudden swelling and behavioral changes.

Feline mammary hyperplasia is a benign, progesterone-associated fibroglandular proliferation of one or more mammary glands that may occur in both the female and male cat . This condition is usually seen in young sexually intact females following estrus, and in male and female cats receiving long-term treatment with progestogens.

Cat Skin Cancer Vet Explained Signs Stages and Treatment
Cat Skin Cancer Vet Explained Signs Stages and Treatment

Cat Swollen and Hot Mammary Glands

What causes swollen and painful mammary glands in my cat ? Swollen, hot, and painful mammary glands in cats are most often a sign of mastitis, an infection of the breast tissue. This condition is common in nursing mothers but can occasionally occur in non-pregnant cats .

As mastitis progresses, the infected mammary gland will become increasingly swollen, inflamed, discolored (frequently red or purple), and painful. The mammary glands may also become ulcerated, with open wounds and scabs visible on the mammary gland.

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Cancer in Cats Causes Symptoms and Treatments

Mastitis in Cats

Mastitis is a painful inflammatory condition in cats . Read our vet-written article to find out more about the causes, treatments and preventatives.

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Cat Mammary Swelling Explained
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