Anal sac adenocarcinoma is a very rare, but aggressive malignant tumor that occurs in dogs and a few cats. As its name suggest, the tumor develops in the tissues of the anal sac. This condition usually affects Dachshund, Springer Spaniel, English Cocker Spaniel, German Shepherd Dog and Alaskan Malamute breeds.

Diagnosis of anal sac adenocarcinoma is made by biopsy. Other helpful tests include needed aspiration biopsy, radiography and ultrasonography.

To treat dogs, aggressive tumor removal through surgery is needed. Chemotherapy and radiation therapy can also help in treatment. However, if the dog is suffering from severe hypercalcaemia, doctors may suggest IV fluid therapy and aminobisphosphonates.

The tumor first appears as a little lump, but can dramatically grow into a large lump. Without any rectal examinations, small tumors are untraceable. However, large tumors cause its victims to experience pain and strain while defecating. Up to 50% of dogs affected with anal sac adenocarcinoma develop hypercalcaemia, which involves symptoms including weight loss, appetite loss, vomiting, slow heart rate and increased drinking as well as increased urination. This condition could develop into the lungs, spleen and lymph nodes.