Canine Breast Cancer
" Canine breast cancer is the most common tumor found in bitches. It is estimated that 50% of all cancers in bitches affect the mammary gland. The prevalence of tumors is considered to be 3 times the levels found in humans. Breast cancer is extremely rare in males and spayed bitches. Both benign and malignant forms of dog breast cancer have been noted. Benign tumors are more common. A single mass or several swellings on the breast, especially on the 4th and 5th nipple may represent a cancerous development. They grow rapidly and cause a severely disturbed morphology and hormonal balance. Other typical signs of cancer include weight loss and progressive loss of body conditions. Physical inspection can not help confirm the type of cancer, so taking a biopsy is essential. Thoracic radiography is highly recommended to study any form of metastases. Tumors can be treated surgically, but there is no consensus about the most effective surgical approach. Chemotherapy and radiation therapy can help, but certain complications have been noted. "
Cause of Canine Breast Cancer:
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.
Types of Canine Breast Cancer:
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:
- Carcinomas: mainly 6 types, with additional sub-types.
- Sarcomas: 4 types
- Carcino–sarcomas: Mixed types of canine breast tumors, vary in type
- Benign Adenomas
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.
Symptoms of Canine Breast Cancer:
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.
Diagnosis of Canine Breast Cancer:
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.
Treatment of Canine Breast Cancer:
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.
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References:
Cancerous Cell Radiography by H. Foreman (Journal of Veterinary Medicine, Volume II – 2007)
R. K. Sharma, et all. Pathology of Cancer (Sudhant Press, India. 2005)
Merck Veterinary Manual (Merck & Co. 2008)
Washington State University College of Veterinary Medicine
