Mammary Gland Hyperplasia in Cats
 
Mammary gland hyperplasia is a benign condition in which an an excessive amount of tissue grows, resulting in enlarged masses in the mammary glands. This is primarily limited to young, sexually intact, cycling, or pregnant queens, but it can also affect cats of either gender after neutering, and cats of either gender that are on progestogen medication.
 
Symptoms and Types
 

Enlargement of one or more mammary glands
Firm, nonpainful masses in the chest, and abdominal area

 
Causes