Apocrine adenocarcinoma, a form of cancer that arises in the anal cells of the apocrine glands or within the sweat glands, shows aggressive characteristics and easily spreads to regional lymph nodes. After lymph node involvement the cancer tends to metastasize onward to the lungs. At the time of diagnosis the tumors usually exhibit a large size, which makes treatment difficult, according to DVM Newsmagazine.
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Description
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Apocrine adenocarcinoma produces a nodule or skin bulge. The tumor is often cystic and filled with fluid. When palpitated, the tumor often feels free-floating and disconnected from the underlying tissue. The tumors appear on the head, neck and anal area of the dog. Apocrine adenocarcinoma of the anal glands tends to be quite large at the time of diagnosis and has usually spread, according to DVM 360.
Symptoms
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Dogs suffering from apocrine adenocarcinoma of the head and neck rarely show any symptoms. Symptoms of the cancer in the anal region remain silent until the tumor is quite large and has often spread. Once the cancer grows to an invasive size the dog my exhibit discomfort in the anal region, muscle weakness, vomiting and lethargy.
Causes
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Apocrine adenocarcinoma arises in older dogs predominantly. Most dogs develop symptoms after age 8. Anal apocrine adenocarcinoma often appears in younger dogs around age 5 and is more prevalent in female dogs. Certain breeds appear to have a strong predisposition toward the cancer. It is seen in Irish setters, the Lhasa apso, shih tzu, collies and English sheepdogs more commonly than other breeds.
Diagnosis
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The veterinarian will evaluate the dog and may perform a needle biopsy of the suspected nodule. Blood work will also be ordered. The veterinarian may need to have X-rays, a CT scan or an ultrasound before he can determine how large the tumor is and whether it has spread to the surrounding area.
Treatment
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The first step in treatment is normally surgical resection of the area. Surrounding lymph nodes may also be removed if they are suspected of containing cancer cells from metastatic spread. If the cancer has spread to the lungs or other major body organs, surgery is usually not performed. Radiation and chemotherapy may be used after surgery or in place of surgery to gain more time for the dog.
Prognosis
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Despite aggressive treatment the dog usually dies from the malignant tumor. Even after surgical resection most dogs live only nine months, according to Canine Cancer Awareness. A few dogs may make three years, but others will often die within weeks of diagnosis.
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