Mammary Carcinoma in Dogs
Mammary carcinoma in dogs is cancer of the mammary glands (breasts). Mammary carcinoma presents several notable symptoms, but these symptoms can be a misleading indicator of a different condition, which is why a vet's diagnosis is essential. Several varieties of the cancer exist, and treatment depends on the progression of the disease. Mammary carcinoma is particularly likely to affect older female dogs.
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Prevalence
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Mammary carcinoma is the second-most common cancer in dogs, after skin cancer. It is especially common in female dogs, who suffer from mammary tumors more often than any other kind of cancer. Older dogs are at especially high risk: the median age for a diagnosis of mammary carcinoma in dogs is 10 years. Dogs under 4 years of age rarely suffer from the disease. The older a dog gets, the higher the odds for developing mammary carcinoma become.
Symptoms
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Mammary tumors can cause swelling of the lymph nodes. This can cause swelling of the limbs, especially the rear ones. The tumors often appear as enlarged knobs of flesh on the mammary glands, or as enlargements of the glands themselves. It is not unusual for a mammary tumor to grow to double its size in a matter of weeks.
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Diagnosis
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Not all mammary tumors are malignant, so it is important that a veterinarian fully examine and diagnose a dog that presents the symptoms of mammary carcinoma. Veterinarians should perform a background analysis of the animal (age, whether sterilized or not, history of pregnancy) along with a thorough physical examination and a complete round of blood tests. In addition to these tests, veterinarians also use radiograph imaging to determine whether or not the cancer has metastasized, and to what extent. Mammary tumors differ to some extent at the cellular level. For example, a mammary sarcoma and a mammary adenocarcinoma will present abnormal growths of mesenchymal and epithelial cells, respectively. Tests also help veterinarians rule out a misdiagnosis of a less-serious condition called mastitis.
Treatment
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The preferred treatment is surgical removal of the cancer. This operation is simpler in dogs than in humans, as mammary tissue in dogs can be removed without any damage to the muscle beneath. Even so, surgery is only a viable option for dogs who are not too elderly or frail for the procedure. If the veterinary surgeon cannot remove the entire cancer, as much as possible is removed to help improve the quality of the animal's life. Chemotherapy is not used as standard treatment in dogs, but is sometimes used if the tumor is not considered operable, or if the tumor removal is not considered curative.
Outlook
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A wide range of factors influence the prognosis for the dog. The size of the tumors is a major factor. Tumors smaller than 1.2 inches rarely recur, while tumors larger than 1.2 inches are likely to recur. The type of tumor is another factor, as some are more difficult to detect and therefore are more more deadly. One study showed that the death rate in dogs diagnosed with this disease is 15.2 percent.
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References
- Photo Credit dog image by jeancliclac from Fotolia.com
