Cancer: Breast

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The exact cause of cancerous developments in a dog's breast is unknown. Different view points exist regarding origin of the disease. It is believed that viruses, hormonal imbalances, genetic defects and nutritional/therapeutic factors can be a possible cause, but none of these have been proven.

Unlike cancers in other parts of the body, canine breast cancers are believed to be truly primary forms, i.e. they originate and develop within the mammary gland. It less common to find secondary cancers in the breast, which refers to cancer that spread from other parts of the body to the dog mammary glands. It is an interesting fact that even benign (slow growing) forms of canine breast cancer are potentially malignant (cancerous) in nature, and cancerous cells can spread to adjoining lymph nodes, lungs, bones and blood circulation through the porous nature of the mammary glands.


These may be either benign, malignant or mixed in nature. More then 50% of all canine breast cancers have been reported to be benign in nature, including benign mixed types; which are potentially malignant.

The World Health Organization (WHO) has classified canine breast cancer as:

The above mentioned types are the basis for all possible combinations of cancerous developments a bitch may suffer from. Most commonly the mixed type of breast cancer is noted, which can be either a “Benign Mix Type”, or “Malignant Mix Type”. In either case, different cells accumulate within the dog mammary gland. Some of these cells are either carcinogenic in nature or may develop into benign tumors, which are potentially malignant in nature, in that they can grow and/or spread rapidly.


On physical examination, tumors appear to be rigid, hard and some times will be a painful swelling. It is very important to know that not all swelling or tumors on a canine breast are cancerous in nature. Many of them may be simple hyperplasia (abnormal increase in the number or normal cells) or any other inflammatory condition.

Dog breast cancer usually grows very rapidly and becomes prominent within the first month, thus reviewing the history of tumor development and growth is essential to suspecting it for a breast cancer.

Malignant forms of  breast cancer in dogs can cause the dog mammary gland to appear irregular and cause a severe disturbance in dog hormones, which worsens the conditions. Moreover, malignant tumors spread to other parts of body, especially within lymphatic tissues, lungs, the thoracic cavity and rarely into circulating blood. A progressive loss of body condition including weakness, weight loss and defective physiology is certain.


Physical examination and history can help in suspecting the presence of canine breast cancer, but confirmation can only be made through a detailed biopsy of tissues, which means a tissue sample will be tested in a laboratory. Detailed biochemical profiles, hormonal studies and histopathology can help in confirming the presence of dog mammary cancer.

For detection of the malignancy, either content from adjoining lymphatic tissues should be studied or thoracic radiography can help in this regard. Differentiation from other diseases such as hyperplasia, hormonal disturbances and inflammation should be made carefully.


Surgery is the most effective way to treat dog breast cancer, but consensus on a single surgical approach is yet to be developed. Different surgical techniques and approaches have been practiced in elimination of breast cancer, such as lumpectomy, simple mastectomy, radical mastectomy, and modified radical mastectomy etc. However, it is a fact that simpler approaches have been proven to be more effective in most cases.

Other options, such as chemotherapy and radiation therapy are applicable, but require detailed studies and are highly specific. Malignancy of dog breast cancer can be controlled by these techniques, but there are several complications too, e.g. severe malignancy of cancer has been noted, if high doses of anti–cancer drugs are used, thus adjuvant chemotherapy is usually preferred.

Homeopathic supplements such as C-Caps Formula  can be helpful during the recovery phase after treatment to improve the prognosis, and help address some of the symptoms.  These types of treatments should be viewed as contributing to a dog's quality of life during recovery.