Diagnosis and Treatment of Canine Breast Cancer
"Canine breast cancer are referred to as neoplastic malignant mammary gland tumors (MGT), which means that they are cancerous and growing uncontrollably. Mammary tumors in dogs are among the most common type of tumor found in intact (unspayed) female dogs (found in 1 in 4 dogs). Approximately 50% - 71% of canine mammary tumors are cancerous, with the other 50% being considered benign or not life threatening. A dogs prognosis (expected life expectancy is based on the nature of the tumor including the tumor size, whether the cancer has spread to nearby lymph nodes and other areas of the body (metastasis), how deep the tumor is into the tissue and the presence of estrogen receptors (estrogen receptors in cells can change cell behavior). If tumors are diagnoses early, and can be successfully removed with surgery, the prognosis is excellent. A veterinarian may recommend other therapies along with surgery including chemotherapy."
Canine Breast Cancer is the most common type of cancer in female dogs. Female dogs have five pairs of mammary glands with the possibility of tumors forming in any one of the glands. Breast cancer can spread from one gland to another. Spaying a female dog dramatically reduces the odds of getting breast cancer if done early in the dog’s life.
Canine breast cancer represents 52% of tumors found in female dogs and have a higher incidence or occurrence in dogs that are between the age of 10 and 11. Half of the dogs with mammary gland tumors will have multiple tumors. Most dogs with a tumor will see the cancer spread to the lungs in 1 to 2 years.
Breeds that are Susceptible to Breast Cancer or Mammary Cancer
- German Shepherds
- Toy and Miniature Poodles
Picture of Dog Breast
Carcinoma in Dog
Diagnosis of Dog Breast Cancer or Canine Mammary Cancer
Your veterinarian will look for visible signs of canine breast
cancer tumors. Signs can include swelling, or soft or hard lumps near
the mammary glands. If tumors are not visible, diagnosis is made when
other symptoms are investigated and a tumor is found to be the cause.
Owners can role their hand down the chest of the abdomen feeling for
any lumps and bumps, rolling the tissue between the fingers. Look for
any hardness in the vicinity of the nipple.
A Fine Needle Aspiration (FSA) test or biopsy is used to take a tissue sample for testing prior to the recommendation of surgery. Though rare, a tumor may look like cancer when in fact it is a benign cyst. The FSA test will allow for a definitive diagnosis.
Other necessary tests include a CBC, chemistry profile,
3-view thoracic X-Rays, which help the veterinary oncologist check if the disease has spread.
Treatment of Breast or Mammary Cancer in Dogs
Surgery is the most common form of treatment for breast cancer
not spread (lumpectomy, mammectomy, mastectomy). Localized cases use
surgery as a complete cure, the case if the tumor is small and the
margins or the tumor are easily identified and removed. Chemotherapy is
used in more advanced cases. Surgery is recommended in cases
where the cancer has spread to the lymph node.
Dog Breast Cancer Tumor Being Prepard for Mammary Surgery
Consult your veterinarian if you see any lumps near the mammary glands. It is possible that tumors are benign (non cancerous). If this is the case, most veterinarians will remove the tumor and then send to a lab for a definitive evaluation.
In addition to surgery, your veterinarian may recommend chemotherapy treatment to make sure that malignant cells (cancer cells that spread quickly) do not spread to the lungs. Chemotherapy drugs such as Adriamycin and oral Cytoxan are used. Recently other drugs such as mitoxantron (Novantrone™) and Adriamycin or Carboplatin (if other drugs are proving to be ineffective) have been used. One study shows that the 2-year survival rate for8 dogs treated with surgery alone was 29% while the survival rate for 8 dogs treated with the chemotherapy medications adjuvant 5-fluouracil and cyclophosphamide was 100%.3
Chemotherapy usually lasts for a span of 6 months with the number of treatments defendant on the severity of the disease (possibly 4 to 6 per week).
Another approach to possibly extend an intact female dogs life with canine breast cancer is not not only have the malignant tumor removed surgically, but to undergo an Ovariohysterectomy (OHE). Recent studies have shown that the benefit could result in a 45% increase in the length of survival after treatment1.
Other approaches that are dependent on tumor type and that should be discussed with your veterinarian include Radiation Therapy, Estrogen Therapy and the use of Cox-2 Inhibitors
Supplements are not a cure, but used as a supportive measure to
speed healing, strengthen healthy cells and to reduce the severity of
symptoms. They are not a specific treatment, but work to strengthen the
body's natural defenses. Supplements used in breast cancer cases
include Inositol hexaphosphate and 1-3-beta glucan. Natural
remedies such as C-Caps
may be of some help as a supportive therapy during
and after treatment. If your dog is undergoing chemotherapy or
radiation do not
use any supplements unless advised by your veterinarian or veterinary
In this case they are best used during the recovery phase after
chemotherapy is completed.
For dogs with large breast tumors (> 3.0 cm), the prognosis tends to be poor since there is an 80% chance of recurrence of the tumor within 6 months after canine breast cancer treatment. The survival rate of dogs with what is termed gross metastasis or widespread spreading of cancer is 5 months. The overall rate of 2 year survival is between 75% and 90%2.
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