Canine Adenocarcinoma Explained

Canine adenocarcinoma is a term for cancers affecting a dog’s glandular tissues. The disease often occurs in the mammary tissues or anal sacs of older female dogs. Although rare, the cancer can also develop in the prostate, anal sacs and mammary tissue of aging male animals. Having a pet with canine adenocarcinoma can be frightening and upsetting for any owner. However, learning more about the disease’s causes, symptoms and treatment options, can help owners make informed decisions on caring for a dog with adenocarcinoma.

Causes and Effects of Canine Adenocarcinoma

Mammary tumors associated with adenocarcinoma are most common in older non-spayed female dogs. Some research suggests a link between the development of mammary tumors and progesterone, the female pregnancy hormone. Since spaying greatly lowers the levels of progesterone, it may also reduce the likelihood of female dog developing the condition.

Malignant mammary tumors are typically inflamed and painful. Often, they appear as a series of hard growths along one or more of a dog’s five mammary glands. The cancer is fast-acting and can spread rapidly throughout the body of an affected animal.

Anal sac adenocarcinoma is less common than cancer of the mammary glands. However, it is an extremely aggressive disease that can progress quickly from the anal sac to the lymph nodes. It can also cause secretions that generate increased levels of calcium in the blood, resulting in kidney damage.

Symptoms of Canine Adenocarcinoma

Dogs with mammary tumors exhibit common symptoms like:

  • A mass made of one or several tumors located under the abdominal skin
  • Swollen, painful, or ulcerated mammary skin
  • Sudden loss of appetite or weight loss
  • Overall weakness
  • Swollen hind legs

Dogs with anal sac adenocarcinoma can display such signs as:

  • Swelling of the perineal region
  • Excessive licking of the perineal region
  • Loss of appetite and weight loss
  • Constipation, discomfort passing stool, or ribbon-like stool

Diagnosis and Treatment of Canine Adenocarcinoma

Diagnosis of mammary or anal sac adenocarcinoma typically consists of a series of tests conducted by animal medical professionals, including:

  • Complete physical exam
  • Blood tests, including a blood count and serum chemistry tests
  • X-ray (radiograph) or ultrasound of the abdominal region

A veterinarian may also recommend a fine-needle aspirate biopsy to determine the kind of tumor or the best course of treatment. This common procedure is generally safe and does not require surgery.

Mammary tumors are generally considered receptive to treatment, particularly when detected early. Surgical removal is one of the most common treatment methods. In certain cases, chemotherapy may be recommended to reduce the risk of reoccurring tumors. An animal medical professional may also consider radiation to treat rare inoperable mammary tumors.

Because of the rapid progression of anal sac adenocarcinoma, treatment usually requires the removal of tumors along with radiation treatment of the affected area and lymph nodes. Although not a cure, both forms of treatment may help improve the quality of life for dogs diagnosed with the disease.