Mammary Gland Enlargement in Cats

While female cats are far more susceptible to these problems, nipple and mammary gland swelling is sometimes seen in male cats as well. A female who is intact is more at risk than a female that is spayed. If unusual mammary gland swelling is noticed while a cat is nursing kittens, veterinary attention may be needed for the kittens along with the mother as the infection can easily spread between the two. 

Nipple and mammary swelling are the outside manifestations of mammary gland enlargement. Most cats have eight nipples, and in the case of enlargement or inflammation, one or more nipples may be affected. 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. 

Generally, when the condition is abnormal and needs treatment, multiple signs may arise. 

• Swelling of the nipples or mammary tissue
• Painful nipples
• Redness
• Discharge from nipples
• Ulceration of the nipples and breast
• Loss of appetite
  
• Fever
  
• Enlarged lymph nodes
• Edema of the skin on hind legs
• Refusal to nurse (if female with kittens)
• Sick kittens (if nursing)

Besides the normal cause of pregnancy, enlarged mammary glands can be the sign of a bigger internal issue in the cat. A veterinarian is best at determining the exact cause of the swelling, which will lead to a faster diagnosis and treatment for the cat. Causes include:

• Pregnancy
• Mastitis (mammary gland infection while lactating)
• Galactostasis (milk collection in mammary gland while weaning)
• Feline Mammary Hypertrophy (benign masses)
• Mammary cancer
• Mammary Hyperplasia (from high levels of progesterone)

A veterinarian will need the cat’s full medical history upon arrival at the clinic. A physical exam will be performed in which the nipples and mammary tissue will be closely examined for signss that match with mammary gland conditions. Some issues may not be serious and might resolve on their own, while other conditions can be life-threatening.

A range of diagnostic testing might be done, generally starting with blood work. This may include a complete blood count and a biochemical profile. A biopsy of the enlarged tissue may be taken for further microscopic evaluation (a histopathological examination). Chest and abdominal X-rays may be needed to check for tumor location and pinpoint any metastasizing (spreading). Urinalysis can be used to confirm and identify any bacteria present in the cat. 

There are a variety of treatments available, depending on the condition present. If the cat is dealing with an infection (as in the cases of mastitis), this can be a medical emergency. Immediate attention is needed to stabilize the cat enough to receive treatment.

Mastitis 

Treatment for mastitis includes an antibiotic prescription to clear up any infection and painkillers to help the cat endure the pain associated with this condition. Your veterinarian may also recommend that you apply a warm compress periodically to help with drainage. 

Mammary Cancer 

This type of cancer is very aggressive and often spreads. It usually occurs in multiple nipples at once. The surgical removal of affected glands (mastectomy) is recommended, especially if the cancer is in its early stages. If the cat is not a good surgical candidate, chemotherapy may be the only treatment option. 

Feline Mammary Hypertrophy 

Advised treatment for this condition is a full spay (ovariohysterectomy). While these surgeries are more routine, if the cat is suffering from poor overall health, the procedure can be very taxing. 

Mammary Hyperplasia

To alleviate this issue, removal of the source of progesterone is needed. This generally leads to an ovariohysterectomy. If ulceration of the glands has occurred, glands may be removed if the cat is stable enough. Painkillers will be prescribed to help the cat get through the days after the surgery. 

Pregnancy or Galactostasis 

Both of these causes of mammary gland enlargement will resolve on their own with time. 

If the underlying condition is mammary cancer, overall prognosis is guarded. This cancer has a high tendency to spread throughout the body, most commonly to the lymph nodes, liver, kidneys, lungs and adrenal glands. If the cancer is caught early and the tumor found is less than 2cm in diameter, surgical removal offers a much higher survival rate than in more advanced cases.

If the cat has received a mastectomy or an ovariohysterectomy, signs of infection need to be watched for. Abide by all recommended at-home care from your vet. A post-surgical clinic visit is often required to allow the veterinarian to check that the healing process is happening successfully. With many of these conditions, spontaneous remissions can occur.