A C
A C
Otherwise known as anal sac gland carcinoma or apocrine gland carcinoma
An anal sac adenocarcinoma is a malignant cancer of the anal gland. It represents approximately 2% of all skin tumors in dogs and is seen predominantly in breeds 10-11 years of age. It often appears as a firm, fixed lump within the anus.
Breeds commonly affected
Paraneoplastic hypercalcemia is a condition where the blood calcium levels increase with the anal sac adenocarcinoma or metastases to the regional lymph nodes. Levels can decrease to normal range within 1-2 days of the surgical removal of the tumor. Recurrence of the hypercalcemia often indicates the recurrence of the tumor or the presence of metastasis.
Studies show that 56-79% of cases have already metastasized to the regional lymph nodes at the time of diagnosis. Other less common sites include the lungs, spleen, bone, pancreas, heart, and mediastinum.
The hypercalcaemic state must be addressed first with fluid therapy.
Surgery involves a wide local removal of the mass. However, this is extremely complicated due to the close proximity to the anal sphincter and rectum. Greater than 50% removal of the anal sphincter can result in transient fecal incontinence. Some lymph nodes can be removed in 50% of the cases.
Unfortunately, 10% f cases experience complications with anal sac resection:
Recommended for cases where the tumor and/or the affected lymph nodes cannot be surgically removed.
The effectiveness of chemotherapy for this cancer is not widely published. It can be used on its own or in combination with radiation therapy.
The prognosis for dogs treated for anal sac adenocarcinoma can range from fair to good depending on the level of disease and treatment undertaken.
Local tumor recurrence occurs in 45-50% of cases within 10 months of surgery.
Anal sac surgery alone | 500 days |
Radiation alone | 657 days |
Surgery and chemotherapy | 540 days |
Surgery, chemotherapy and radiation therapy | 742-956 days |
Factors that worsen the prognosis