Benign and malignant tumors of the mammary glands
occur fairly frequently in unspayed female dogs, in fact they are the
most common type of tumor in the group. Spaying can largely reduce the
risk of developing this type of cancer, especially if the dog is spayed
before it has an opportunity to go into heat. There are two main types
of mammary gland breast tumors, each with several subtypes of tumor
growth.
The mammary glands' function is to produce milk to feed newborn
puppies. They are located in two rows that extend from the chest to the
lower abdominal area; the nipples indicate their location on the trunk
of the body. While this condition is more likely to occur in the female
population, it does also affect male dogs, albeit rarely. When a male
dog is affected by a tumor of the breast, the prognosis is much more guarded and grave.